diff --git a/.github/workflows/reusable_release.yml b/.github/workflows/reusable_release.yml
index b2539a0..6054b4d 100644
--- a/.github/workflows/reusable_release.yml
+++ b/.github/workflows/reusable_release.yml
@@ -124,6 +124,7 @@ jobs:
     name: Publish
     runs-on: ubuntu-latest
     needs: release
+    if: ${{ inputs.dry_run == false }}
     steps:
       - name: Download Package
         uses: actions/download-artifact@v4
diff --git a/assets/scripts/@types/index.d.ts b/assets/scripts/@types/index.d.ts
index 99ea1f8..ae9d797 100644
--- a/assets/scripts/@types/index.d.ts
+++ b/assets/scripts/@types/index.d.ts
@@ -3,6 +3,7 @@ declare global {
   const _: _.UnderscoreStatic;
 
   interface Window {
+    wc_address_i18n_params: any;
     wp: {
       template: (id: string) => _.CompiledTemplate;
     };
diff --git a/assets/scripts/frontend/controllers/address-page.controller.ts b/assets/scripts/frontend/controllers/address-page.controller.ts
index ff9b59e..fdb4a35 100644
--- a/assets/scripts/frontend/controllers/address-page.controller.ts
+++ b/assets/scripts/frontend/controllers/address-page.controller.ts
@@ -1,25 +1,77 @@
 const $ = jQuery;
 
 export default class AddressPageController {
-  private $inputs: JQuery<HTMLInputElement>;
+  private selector = '.entity-type-control input';
+  private locale: Record<string, string>;
 
   public init(): void {
-    this.$inputs = $('.entity-type-control input[type="radio"]');
+    this.locale = JSON.parse(window.wc_address_i18n_params.locale_fields);
   }
 
   public finalize(): void {
-    this.$inputs.on('click', ({ currentTarget }) =>
-      this.toggleFields($(currentTarget)),
+    $(document.body).on('change refresh', this.selector, (e) => {
+      console.log('change refresh');
+      this.toggleEntityType($(e.target));
+    });
+
+    $(document.body).on('country_to_state_changing', () => {
+      window.setTimeout(
+        () => this.toggleEntityType($(`${this.selector}:checked`)),
+        100,
+      );
+      console.log('country_to_state_changing');
+    });
+  }
+
+  private toggleEntityType($input: JQuery<HTMLInputElement>): void {
+    const isCompany = $input.val() === 'company';
+
+    console.log($input.is(':checked'), $input.val());
+
+    this.isRequired($<HTMLParagraphElement>('.entity-type-toggle'), isCompany);
+  }
+
+  private isRequired(
+    $field: JQuery<HTMLParagraphElement>,
+    required: boolean,
+  ): void {
+    $field.find('input').prop({
+      'aria-required': required,
+      disabled: !required,
+    });
+
+    if (required) {
+      $field.find('label .optional').remove();
+      $field.addClass('shown validate-required');
+
+      if ($field.find('label .required').length === 0) {
+        $field
+          .find('label')
+          .append(
+            `<abbr class="required" title="${window.wc_address_i18n_params.i18n_required_text}">*</abbr>`,
+          );
+      }
+
+      return;
+    }
+
+    $field.find('label .required').remove();
+    $field.removeClass(
+      'shown validate-required woocommerce-invalid woocommerce-invalid-required-field',
     );
-    this.toggleFields(this.$inputs.filter(':checked'));
+
+    if ($field.find('label .optional').length === 0) {
+      $field
+        .find('label')
+        .append(
+          `<abbr class="optional" title="${window.wc_address_i18n_params.i18n_optional_text}">${window.wc_address_i18n_params.i18n_optional_text}</abbr>`,
+        );
+    }
   }
 
   private toggleFields($toggle: JQuery<HTMLInputElement>): void {
     const isPerson = $toggle.attr('value') === 'person';
 
-    $('.hide-if-person').toggleClass('shown', !isPerson).find('input').prop({
-      required: !isPerson,
-      disabled: isPerson,
-    });
+    $('.hide-if-person').toggleClass('shown', !isPerson);
   }
 }
diff --git a/assets/styles/components/_billing_fields.scss b/assets/styles/components/_billing_fields.scss
index 90296ca..285a6de 100644
--- a/assets/styles/components/_billing_fields.scss
+++ b/assets/styles/components/_billing_fields.scss
@@ -15,11 +15,11 @@
       }
     }
 
-    .hide-if-person {
-      display: none;
+    .entity-type-toggle {
+      display: none !important;
 
       &.shown {
-        display: block;
+        display: block !important;
       }
     }
   }
diff --git a/composer.json b/composer.json
index b6aa19b..cb4c03b 100644
--- a/composer.json
+++ b/composer.json
@@ -20,13 +20,19 @@
   },
   "autoload": {
     "psr-4": {
-      "Oblak\\WooCommerce\\Serbian_Addons\\": "lib"
+      "Oblak\\WCSRB\\": "lib/"
     },
+    "classmap": [
+      "lib/Admin/",
+      "lib/Gateway/",
+      "lib/QR/"
+    ],
     "files": [
-      "lib/Utils/wcsrb-core.php",
-      "lib/Utils/wcsrb-helpers.php",
-      "lib/Utils/wcsrb-payment-slip.php",
-      "lib/Utils/wcsrb-settings.php"
+      "lib/Functions/wcsrb-address-field-fns.php",
+      "lib/Functions/wcsrb-core.php",
+      "lib/Functions/wcsrb-helpers.php",
+      "lib/Functions/wcsrb-payment-slip.php",
+      "lib/Functions/wcsrb-settings.php"
     ]
   },
   "config": {
diff --git a/config/assets.php b/config/assets.php
index e0e6888..675e0eb 100644
--- a/config/assets.php
+++ b/config/assets.php
@@ -23,6 +23,6 @@
     'base_uri' => plugins_url( 'dist', WCRS_PLUGIN_BASE ),
     'id'       => 'wcrs',
     'manifest' => 'assets.php',
-    'priority' => 50,
+    'priority' => 500,
     'version'  => WCRS_VERSION,
 );
diff --git a/lib/Admin/Edit_User_Controller.php b/lib/Admin/Edit_User_Controller.php
new file mode 100644
index 0000000..24bec75
--- /dev/null
+++ b/lib/Admin/Edit_User_Controller.php
@@ -0,0 +1,60 @@
+<?php
+/**
+ * Edit_User_Controller class file.
+ *
+ * @package Serbian Addons for WooCommerce
+ */
+
+namespace Oblak\WCSRB\Admin;
+
+use Oblak\WP\Abstracts\Hook_Caller;
+use Oblak\WP\Decorators\Filter;
+use Oblak\WP\Decorators\Hookable;
+
+/**
+ * Changes the fields on the checkout page
+ *
+ * @since 3.8.0
+ */
+#[Hookable( 'admin_init', 99 )]
+class Edit_User_Controller extends Hook_Caller {
+    /**
+     * Adds the company information to the customer meta fields.
+     *
+     * @param  array $fields Customer meta fields.
+     * @return array         Modified customer meta fields
+     */
+    #[Filter( 'woocommerce_customer_meta_fields' )]
+    public function modify_customer_meta_fields( array $fields ): array {
+        $company = \array_search( 'billing_company', \array_keys( $fields['billing']['fields'] ), true );
+
+        //phpcs:disable SlevomatCodingStandard.Arrays.AlphabeticallySortedByKeys.IncorrectKeyOrder
+        $fields['billing']['fields'] = \array_merge(
+            \array_slice( $fields['billing']['fields'], 0, $company ),
+            array(
+                'billing_type'    => array(
+                    'description' => '',
+                    'label'       => \__( 'Customer type', 'serbian-addons-for-woocommerce' ),
+                    'options'     => \wcsrb_get_entity_types(),
+                    'type'        => 'select',
+                ),
+                'billing_company' => $fields['billing']['fields']['billing_company'],
+                'billing_mb'      => array(
+                    'description' => '',
+                    'label'       => \__( 'Company Number', 'serbian-addons-for-woocommerce' ),
+                    'type'        => 'text',
+                ),
+                'billing_pib'     => array(
+                    'description' => '',
+                    'label'       => \__( 'Tax Number', 'serbian-addons-for-woocommerce' ),
+                    'type'        => 'text',
+                ),
+
+            ),
+            \array_slice( $fields['billing']['fields'], $company ),
+        );
+        //phpcs:enable SlevomatCodingStandard.Arrays.AlphabeticallySortedByKeys.IncorrectKeyOrder
+
+        return $fields;
+    }
+}
diff --git a/lib/Serbian_WooCommerce.php b/lib/App.php
similarity index 83%
rename from lib/Serbian_WooCommerce.php
rename to lib/App.php
index 220a03b..129bbc1 100644
--- a/lib/Serbian_WooCommerce.php
+++ b/lib/App.php
@@ -5,8 +5,10 @@
  * @package Serbian Addons for WooCommerce
  */
 
-namespace Oblak\WooCommerce\Serbian_Addons;
+namespace Oblak\WCSRB;
 
+use Oblak\WCSRB\Services\Field_Validator;
+use Oblak\WooCommerce\Serbian_Addons as Legacy;
 use Oblak\WP\Decorators\Action;
 use Oblak\WP\Decorators\Filter;
 use Oblak\WP\Traits\Hook_Processor_Trait;
@@ -16,7 +18,7 @@
 /**
  * Main plugin class
  */
-class Serbian_WooCommerce {
+class App {
     use Hook_Processor_Trait;
     use Settings_API_Methods;
     use Singleton;
@@ -29,6 +31,13 @@ class Serbian_WooCommerce {
      */
     public string $version = WCRS_VERSION;
 
+    /**
+     * Field validator instance.
+     *
+     * @var Field_Validator
+     */
+    protected Field_Validator $validator;
+
     /**
      * Private constructor
      */
@@ -43,11 +52,12 @@ protected function __construct() {
      */
     protected function get_dependencies(): array {
         return array(
-            Admin\Admin_Core::class,
-			Core\Template_Extender::class,
-            Checkout\Field_Customizer::class,
-            Checkout\Field_Validator::class,
-            Order\Field_Display::class,
+            Admin\Edit_User_Controller::class,
+            Core\Address_Display_Controller::class,
+            Core\Address_Field_Controller::class,
+            Core\Address_Validate_Controller::class,
+            Utils\Template_Extender::class,
+            Legacy\Admin\Admin_Core::class,
         );
     }
 
@@ -63,9 +73,9 @@ public function run_hooks() {
      */
     #[Action( tag: 'plugins_loaded', priority: 1000 )]
     public function on_plugins_loaded() {
-        Core\Installer::instance()->init();
+        Utils\Installer::instance()->init();
 
-        $s = \load_plugin_textdomain(
+        \load_plugin_textdomain(
             domain: 'serbian-addons-for-woocommerce',
             plugin_rel_path: \dirname( WCRS_PLUGIN_BASE ) . '/languages',
         );
@@ -78,7 +88,7 @@ public function on_plugins_loaded() {
     public function load_plugin_settings() {
         try {
             $this->load_options( 'wcsrb_settings' );
-        } catch ( \Exception ) {
+        } catch ( \Exception | \Error ) {
             \wc_get_logger()->critical(
                 'Failed to load plugin settings',
                 array(
@@ -133,7 +143,7 @@ public function declare_hpos_compatibility() {
      */
     #[Filter( tag: 'woocommerce_payment_gateways', priority: 50 )]
     public function add_payment_gateways( $gateways ) {
-        $gateways[] = Gateway\Gateway_Payment_Slip::class;
+        $gateways[] = Legacy\Gateway\Gateway_Payment_Slip::class;
         return $gateways;
     }
 
@@ -173,4 +183,13 @@ public function check_asset_necessity( bool $load, string $script ) {
             default => $load,
         };
     }
+
+    /**
+     * Gets the field validator instance.
+     *
+     * @return Field_Validator
+     */
+    public function validator(): Field_Validator {
+        return $this->validator ??= new Field_Validator();
+    }
 }
diff --git a/lib/Checkout/Field_Customizer.php b/lib/Checkout/Field_Customizer.php
deleted file mode 100644
index f97e8fc..0000000
--- a/lib/Checkout/Field_Customizer.php
+++ /dev/null
@@ -1,208 +0,0 @@
-<?php
-/**
- * Field_Customizer class file.
- *
- * @package Serbian Addons for WooCommerce
- * @subpackage WooCommerce\Checkout
- */
-
-namespace Oblak\WooCommerce\Serbian_Addons\Checkout;
-
-use Oblak\WP\Abstracts\Hook_Caller;
-use Oblak\WP\Decorators\Filter;
-use Oblak\WP\Decorators\Hookable;
-
-/**
- * Changes the fields on the checkout page
- */
-#[Hookable( 'woocommerce_init', 99 )]
-class Field_Customizer extends Hook_Caller {
-    /**
-     * Modifies the default customer type to person in the edit address form.
-     *
-     * @param  mixed  $value Field value.
-     * @param  string $key   Field key.
-     * @return mixed
-     */
-    #[Filter( tag: 'woocommerce_my_account_edit_address_field_value', priority: 100 )]
-    public function modify_default_customer_type( mixed $value, string $key ): mixed {
-        if ( 'billing_type' === $key && ! $value ) {
-            $value = 'person';
-        }
-
-        return $value;
-    }
-
-    /**
-     * Modifies the billing fields to add the customer type and additional company fields
-     *
-     * @param  array $fields Billing fields.
-     * @return array         Modified billing fields
-     */
-    #[Filter( tag: 'woocommerce_billing_fields', priority: 'woocommerce_serbian_checkout_fields_priority' )]
-    public function modify_billing_fields( $fields ) {
-        $enabled_type = \WCSRB()->get_settings( 'core', 'enabled_customer_types' );
-
-        $fields = $this->maybe_remove_fields( $fields );
-
-        $fields['billing_type'] = $this->add_billing_type_field( $enabled_type );
-
-        $fields = \array_merge(
-            $fields,
-            $this->maybe_add_company_fields( $enabled_type ),
-        );
-
-        // If the billing type is not both or company, remove the company field.
-        if ( ! \in_array( $enabled_type, array( 'both', 'company' ), true ) ) {
-            unset( $fields['billing_company'] );
-        } else { // Else, addin some extra data.
-            $fields['billing_company']['class'][]  = 'hide-if-person';
-            $fields['billing_company']['required'] = true;
-        }
-
-        return $fields;
-    }
-
-    /**
-     * Modifies shipping fields to remove the unneded fields.
-     *
-     * @param  array $fields Shipping fields.
-     * @return array         Modified shipping fields
-     */
-    #[Filter( tag: 'woocommerce_shipping_fields', priority: 'woocommerce_serbian_checkout_fields_priority' )]
-    public function modify_shipping_fields( $fields ) {
-        $fields = $this->maybe_remove_fields( $fields, 'shipping' );
-
-        return $fields;
-    }
-
-    /**
-     * Removes unnecessary fields from the checkout ajax request
-     *
-     * @param  array $fields Fields to modify.
-     * @return array         Modified fields
-     */
-    #[Filter( tag: 'woocommerce_shipping_fields', priority: 'woocommerce_serbian_checkout_fields_priority' )]
-    public function modify_ajax_checkout_fields( $fields ) {
-        if ( ! \wp_doing_ajax() ) {
-            return $fields;
-        }
-
-        $checkout_customer_type = \xwp_fetch_post_var( 'billing_type', 'person' );
-
-        if ( 'person' === $checkout_customer_type ) {
-            unset( $fields['billing']['billing_company'] );
-            unset( $fields['billing']['billing_mb'] );
-            unset( $fields['billing']['billing_pib'] );
-        }
-
-        return $fields;
-    }
-
-    /**
-     * Removes the fields that are not needed, and changes fields priority.
-     *
-     * @param  array  $fields Fields.
-     * @param  string $type   Field type - billing or shipping.
-     * @return array          Modified fields
-     */
-    private function maybe_remove_fields( $fields, $type = 'billing' ) {
-        $fields[ "{$type}_postcode" ]['priority'] = 81;
-        $fields[ "{$type}_city" ]['priority']     = 91;
-        $fields[ "{$type}_country" ]['priority']  = 91;
-
-        $to_remove = \WCSRB()->get_settings(
-            'core',
-            'remove_unneeded_fields',
-        ) ? array( 'address_2', 'state' ) : array();
-
-        /**
-         * Filters the fields that should be removed from the checkout page
-         *
-         * @param  array $to_remove Fields to remove
-         * @return array
-         * @since 1.3.0
-         */
-        $to_remove = \apply_filters( 'woocommerce_serbian_checkout_fields_to_remove', $to_remove );
-
-        foreach ( $to_remove as $field_name ) {
-            unset( $fields[ "{$type}_{$field_name}" ] );
-        }
-
-        return $fields;
-    }
-
-    /**
-     * Adds the billing type field to the checkout page.
-     *
-     * Depending on the plugin settings, field can be a radio button or a hidden input
-     *
-     * @param  string $enabled_type Enabled customer type.
-     * @return array                Billing type field data.
-     *
-     * @since 1.3.0
-     */
-    private function add_billing_type_field( $enabled_type ) {
-        $billing_type = array(
-            'class'    => array( 'form-row-wide', 'entity-type-control', 'update_totals_on_change' ),
-            'default'  => 'person',
-            'label'    => \__( 'Customer type', 'serbian-addons-for-woocommerce' ),
-            'options'  => \wcsrb_get_entity_types(),
-            'priority' => 21,
-            'required' => true,
-            'type'     => 'radio',
-        );
-
-        if ( 'both' !== $enabled_type ) {
-
-            $billing_type['type']        = 'hidden';
-            $billing_type['default']     = $enabled_type;
-            $billing_type['description'] = \wcsrb_get_entity_types()[ $enabled_type ];
-
-            unset( $billing_type['options'] );
-
-        }
-
-        return $billing_type;
-    }
-
-    /**
-     * Add needed company fields if the customer can checkout as a company
-     *
-     * @param  string $enabled_type Enabled customer type.
-     * @return array                Company fields data.
-     */
-    private function maybe_add_company_fields( $enabled_type ) {
-        if ( ! \in_array( $enabled_type, array( 'both', 'company' ), true ) ) {
-            return array();
-        }
-
-        $extra_fields = array(
-            'billing_mb'  => array(
-                'class'       => array( 'form-row-first', 'hide-if-person' ),
-                'label'       => \__( 'Company Number', 'serbian-addons-for-woocommerce' ),
-                'placeholder' => \__( 'Enter MB', 'serbian-addons-for-woocommerce' ),
-                'priority'    => 31,
-                'required'    => true,
-                'type'        => 'text',
-                'validate'    => array( 'mb' ),
-            ),
-            'billing_pib' => array(
-                'class'       => array( 'form-row-last', 'hide-if-person' ),
-                'label'       => \__( 'Tax Number', 'serbian-addons-for-woocommerce' ),
-                'placeholder' => \__( 'Enter PIB', 'serbian-addons-for-woocommerce' ),
-                'priority'    => 32,
-                'required'    => true,
-                'type'        => 'text',
-                'validate'    => array( 'pib' ),
-            ),
-        );
-
-        if ( 'company' !== $enabled_type ) {
-            $extra_fields['billing_pib']['custom_attributes']['disabled'] = 'disabled';
-            $extra_fields['billing_mb']['custom_attributes']['disabled']  = 'disabled';
-        }
-
-        return $extra_fields;
-    }
-}
diff --git a/lib/Checkout/Field_Validator.php b/lib/Checkout/Field_Validator.php
deleted file mode 100644
index 567c256..0000000
--- a/lib/Checkout/Field_Validator.php
+++ /dev/null
@@ -1,161 +0,0 @@
-<?php
-/**
- * Field_Validator class file.
- *
- * @package Serbian Addons for WooCommerce
- * @subpackage WooCommerce\Checkout
- */
-
-namespace Oblak\WooCommerce\Serbian_Addons\Checkout;
-
-use Oblak\WP\Decorators\Action;
-use Oblak\WP\Decorators\Hookable;
-
-/**
- * Handles checkout field validation
- */
-#[Hookable( 'woocommerce_init', 99 )]
-class Field_Validator {
-    /**
-     *  Constructor
-     */
-    public function __construct() {
-        if ( \class_exists( '\XWP\Hook\Invoker' ) ) {
-            return;
-        }
-
-        \xwp_invoke_hooked_methods( $this );
-    }
-    /**
-     * Adds custom validation to billing address field saving
-     *
-     * @param  int    $user_id Current User ID.
-     * @param  string $type    Address type being edited - billing or shipping.
-     */
-    #[Action( 'woocommerce_after_save_address_validation', 99 )]
-    public function validate_saved_address( int $user_id, string $type ) {
-        $posted = \xwp_post_arr();
-
-        // If we're not validating billing, we don't need to do anything.
-        if ( ! $this->can_validate( $posted, $type ) ) {
-            return;
-        }
-
-        $validators = $this->get_field_validators( \current_filter() );
-        $notices    = $this->filter_notices( \array_keys( $validators ) );
-
-        foreach ( $validators as $field => $args ) {
-            if ( $args['validator']( $posted[ $field ] ) ) {
-                continue;
-            }
-
-            $notices['error'][] = array(
-                'data'   => array(
-                    'id' => $field,
-                ),
-                'notice' => $args['message'],
-            );
-
-            $_POST[ $field ] = '';
-
-        }
-        \WC()->session->set( 'wc_notices', $notices );
-    }
-
-
-    /**
-     * Adds custom validation to billing address field saving
-     *
-     * @param  array     $data  Posted data.
-     * @param  \WP_Error $error Error object.
-     */
-    #[Action( 'woocommerce_after_checkout_validation', 0 )]
-    public function validate_checkout_fields( $data, $error ) {
-        $fields = $this->get_field_validators( \current_filter() );
-
-        foreach ( \array_keys( $fields ) as $field ) {
-            $error->remove( $field . '_required' );
-        }
-
-        if ( ! $this->can_validate( $data ) ) {
-            return;
-        }
-
-        foreach ( $fields as $field => $args ) {
-            if ( $args['validator']( $data[ $field ] ) ) {
-                continue;
-            }
-
-            $error->add( $args['code'], $args['message'], array( 'id' => $field ) );
-        }
-    }
-
-    /**
-     * Checks if the current address can be validated.
-     *
-     * @param  array  $fields    Address fields.
-     * @param  string $addr_type Address type being validated.
-     * @return bool
-     */
-    protected function can_validate( array $fields, string $addr_type = 'billing' ): bool {
-        $type    = $fields['billing_type'] ??= '';
-        $country = $fields['billing_country'] ??= '';
-
-        return 'billing' === $addr_type && 'company' === $type && 'RS' === $country;
-    }
-
-    /**
-     * Returns the field validators for the given action.
-     *
-     * @param  string $action Action being performed.
-     * @return array
-     */
-    protected function get_field_validators( string $action ) {
-        $args = array(
-            'billing_company' => array(
-                'code'      => 'billing_company_required',
-                'message'   => \__( 'Company name is required', 'serbian-addons-for-woocommerce' ),
-                'validator' => static fn( $val ) => '' !== $val,
-            ),
-            'billing_mb'      => array(
-                'code'      => 'billing_mb_validation',
-                'message'   => \__( 'Company number is invalid', 'serbian-addons-for-woocommerce' ),
-                'validator' => '\Oblak\validateMB',
-            ),
-            'billing_pib'     => array(
-                'code'      => 'billing_pib_validation',
-                'message'   => \__( 'Company Tax Number is invalid', 'serbian-addons-for-woocommerce' ),
-                'validator' => '\Oblak\validatePIB',
-            ),
-        );
-
-        /**
-         * Returns the validation arguments for the given action.
-         *
-         * @param array  $args   Validation arguments.
-         * @param string $action Action being performed.
-         *
-         * @return array
-         *
-         * @since 3.6.0
-         */
-        return \apply_filters( 'wcrs_field_validators', $args, $action );
-    }
-
-    /**
-     * Filters out notices for fields that have been validated.
-     *
-     * @param  array $fields Fields that have been validated.
-     * @return array
-     */
-    protected function filter_notices( array $fields ): array {
-        $notices = \WC()->session->get( 'wc_notices', array() );
-
-        $notices['error'] = \array_filter(
-            $notices['error'] ?? array(),
-            static fn( $e ) => ! \in_array( $e['data']['id'] ?? '', $fields, true )
-        );
-
-        return $notices;
-    }
-}
diff --git a/lib/Core/Address_Display_Controller.php b/lib/Core/Address_Display_Controller.php
new file mode 100644
index 0000000..450ede2
--- /dev/null
+++ b/lib/Core/Address_Display_Controller.php
@@ -0,0 +1,145 @@
+<?php //phpcs:disable Universal.Operators.DisallowShortTernary.Found
+
+namespace Oblak\WCSRB\Core;
+
+use Oblak\WP\Abstracts\Hook_Caller;
+use Oblak\WP\Decorators\Filter;
+use Oblak\WP\Decorators\Hookable;
+use WC_Customer;
+use WC_Order;
+
+/**
+ * Changes the fields on the checkout page
+ *
+ * @since 3.8.0
+ */
+#[Hookable( 'woocommerce_init', 99 )]
+class Address_Display_Controller extends Hook_Caller {
+    /**
+     * Modifies the address format for Serbia to include necessary company information
+     *
+     * @param  array<string,string> $formats Address formats.
+     * @return array<string,string>
+     */
+    #[Filter( 'woocommerce_localisation_address_formats', 'wcrs_localization_address_priority' )]
+    public function modify_address_format( $formats ) {
+        \add_filter( 'woocommerce_formatted_address_force_country_display', '__return_true' );
+
+        $formats['RS'] = "{name}\n{company}\n{mb}\n{pib}\n{address_1}\n{address_2}\n{postcode} {city}, {state} {country}";
+
+        if ( \WCSRB()->get_settings( 'core', 'remove_unneeded_fields' ) ) {
+            $formats['RS'] = \str_replace( array( '{state}', '{address_2}' ), '', $formats['RS'] );
+        }
+
+        return $formats;
+    }
+
+    /**
+     * Adds custom replacements to the replacements array.
+     *
+     * Custom fields added are:
+     *  - Type
+     *  - Company Number
+     *  - Tax Identification Number
+     *
+     * @param  string[] $replacements  Replacements array.
+     * @param  array    $args          Address data.
+     * @return string[]                Modified replacements array
+     */
+    #[Filter( 'woocommerce_formatted_address_replacements', 99 )]
+    public function modify_address_replacements( $replacements, $args ) {
+        $replacements['{mb}']  = $args['mb'] ?? "\n";
+        $replacements['{pib}'] = $args['pib'] ?? "\n";
+
+        return $replacements;
+    }
+
+    /**
+     * Modifies the address data array to include neccecary company information.
+     *
+     * This is used in the My Account > Addresses page.
+     *
+     * @param  array<string, string> $fmtd Address data array.
+     * @param  int                   $uid     Customer ID.
+     * @param  'billing'|'shipping'  $type    Address type (billing or shipping).
+     * @return array
+     */
+    #[Filter( 'woocommerce_my_account_my_address_formatted_address', 99 )]
+    public function modify_account_formatted_address( array $fmtd, int $uid, $type ) {
+        if ( 'billing' !== $type ) {
+            return $fmtd;
+        }
+
+        return \array_merge(
+            $fmtd,
+            $this->get_replacement_values( new WC_Customer( $uid ) ),
+        );
+    }
+
+    /**
+     * Modifies the address data array to include neccecary company information.
+     *
+     * This is used for the order addresses.
+     *
+     * @param  array    $address Address data array.
+     * @param  WC_Order $order   Order object.
+     * @return array             Modified address data array
+     */
+    #[Filter( 'woocommerce_order_formatted_billing_address', 99 )]
+    public function modify_order_formatted_address( $address, $order ) {
+        return \array_merge(
+            $address,
+            $this->get_replacement_values( $order ),
+        );
+    }
+
+    /**
+     * Modifies the buyer name in the admin order page to include necessary company information
+     *
+     * @param  string   $buyer Buyer name.
+     * @param  WC_Order $order Order object.
+     * @return string          Modified Buyer name
+     */
+    #[Filter( 'woocommerce_admin_order_buyer_name', 99 )]
+    public function modify_order_buyer_name( string $buyer, WC_Order $order ): string {
+        $data = \wcsrb_get_company_data( $order );
+
+        if ( 'RS' === $order->get_billing_country() && 'company' === $data['type'] ) {
+            $buyer = $order->get_billing_company();
+        }
+
+        return $buyer;
+    }
+
+    /**
+     * Billing address modifier function
+     *
+     * Depending on the customer(user) type we add the needed rows to the address.
+     * If the customer is a company we prepend the number type before the number itself
+     *
+     * @param WC_Customer|WC_Order $target Customer or Order object.
+     * @return array<string, string>
+     */
+    protected function get_replacement_values( WC_Customer|WC_Order $target ): array {
+        $data = \wcsrb_get_company_data( $target );
+        if ( 'company' !== $data['type'] ) {
+            return array();
+        }
+
+        return array(
+            'first_name' => "\n",
+            'last_name'  => "\n",
+            'mb'         => \sprintf(
+                '%s: %s',
+                \_x( 'Company Number', 'Address display', 'serbian-addons-for-woocommerce' ),
+                $data['mb'] ?: "\n",
+            ),
+            'pib'        => \sprintf(
+                '%s: %s',
+                \_x( 'Tax Identification Number', 'Address display', 'serbian-addons-for-woocommerce' ),
+                $data['pib'] ?: "\n",
+            ),
+
+        );
+    }
+}
diff --git a/lib/Core/Address_Field_Controller.php b/lib/Core/Address_Field_Controller.php
new file mode 100644
index 0000000..a7b3354
--- /dev/null
+++ b/lib/Core/Address_Field_Controller.php
@@ -0,0 +1,194 @@
+<?php
+/**
+ * Address_Field_Controller class file.
+ *
+ * @package Serbian Addons for WooCommerce
+ */
+
+namespace Oblak\WCSRB\Core;
+
+use Oblak\WP\Abstracts\Hook_Caller;
+use Oblak\WP\Decorators\Filter;
+use Oblak\WP\Decorators\Hookable;
+
+/**
+ * Changes the fields on the checkout page
+ *
+ * @since 3.8.0
+ */
+#[Hookable( 'woocommerce_init', 99 )]
+class Address_Field_Controller extends Hook_Caller {
+    /**
+     * Adds the customer type field to the default address fields.
+     *
+     * @param  array<string,array> $fields Default address fields.
+     * @return array<string,array>
+     */
+    #[Filter( tag: 'woocommerce_default_address_fields', priority: 999999 )]
+    public function add_customer_type_field( array $fields ): array {
+        $enabled_type = \WCSRB()->get_settings( 'core', 'enabled_customer_types' );
+        $type_field   = array(
+            'class'    => array( 'form-row-wide', 'entity-type-control', 'update_totals_on_change', 'address-field' ),
+            'default'  => 'person',
+            'label'    => \__( 'Customer type', 'serbian-addons-for-woocommerce' ),
+            'options'  => \wcsrb_get_entity_types(),
+            'priority' => 21,
+            'required' => true,
+            'type'     => 'radio',
+        );
+
+        if ( 'both' !== $enabled_type ) {
+
+            $type_field = \array_merge(
+                $type_field,
+                array(
+                    'default'     => $enabled_type,
+                    'description' => \wcsrb_get_entity_types()[ $enabled_type ],
+                    'type'        => 'hidden',
+                    'value'       => $enabled_type,
+                ),
+            );
+
+            unset( $type_field['options'] );
+        }
+
+        $fields['type'] = $type_field;
+
+        return $fields;
+    }
+
+    /**
+     * Adds the extra fields to the default address fields
+     *
+     * @param  array<string,array> $fields Default address fields.
+     * @return array<string,array>
+     */
+    #[Filter( tag: 'woocommerce_default_address_fields', priority: 'wcsrb_address_fields_priority' )]
+    public function add_company_fields( array $fields ): array {
+        if ( \WCSRB()->get_settings( 'core', 'remove_unneeded_fields' ) ) {
+            unset( $fields['address_2'], $fields['state'] );
+        }
+
+        $fields['company']['class'][] = 'entity-type-toggle';
+
+        return \array_merge( $fields, \wcsrb_get_company_fields() );
+    }
+
+    /**
+     * Unsets I18n label for the customer type field.
+     *
+     * @param  array<string, array> $fields Default country locale fields.
+     * @return array<string, array>
+     */
+    #[Filter( tag: 'woocommerce_get_country_locale_default', priority: 999999 )]
+    public function modify_default_locale_field_data( array $fields ): array {
+        unset( $fields['type']['label'] );
+
+        return $fields;
+    }
+
+    /**
+     * Set the JS locale fields data.
+     *
+     * Adds the hidden and required properties for all countries.
+     * All are set to be hidden and NOT required by default.
+     *
+     * @param  array<string, array> $locale Default locale fields data.
+     * @return array<string, array>
+     */
+    #[Filter( tag: 'woocommerce_get_country_locale', priority: 1000 )]
+    public function add_default_locale_field_data( array $locale ): array {
+        foreach ( $locale as &$fields ) {
+            $fields['company']['required'] = false;
+            $fields['type']                = array(
+                'hidden'   => true,
+                'required' => false,
+            );
+            $fields['mb']                  = array(
+                'hidden'   => true,
+                'required' => false,
+            );
+            $fields['pib']                 = array(
+                'hidden'   => true,
+                'required' => false,
+            );
+        }
+
+        return $locale;
+    }
+
+    /**
+     * Adds the custom locale field data
+     *
+     * We unhide the fields and enable them only if the company type is active.
+     *
+     * @param  array<string, array> $locale Default locale fields data.
+     * @return array<string, array>
+     */
+    #[Filter( tag: 'woocommerce_get_country_locale', priority: 1000 )]
+    public function add_custom_locale_field_data( array $locale ): array {
+        $company_active = \wcsrb_can_checkout_as( 'company' );
+        $company_props  = array( 'hidden' => ! $company_active );
+
+        // phpcs:disable SlevomatCodingStandard.Arrays.AlphabeticallySortedByKeys.IncorrectKeyOrder
+        $locale['RS'] = array(
+            'type'     => array(
+                'required' => true,
+                'hidden'   => false,
+            ),
+            'company'  => \array_merge(
+                array( 'class' => array( 'form-row-wide', 'entity-type-toggle', 'shown' ) ),
+                $company_props,
+            ),
+            'mb'       => $company_props,
+            'pib'      => $company_props,
+            'postcode' => array(
+                'priority' => 81,
+            ),
+            'city'     => array(
+                'priority' => 82,
+            ),
+            'country'  => array(
+                'priority' => 91,
+            ),
+        );
+        // phpcs:enable SlevomatCodingStandard.Arrays.AlphabeticallySortedByKeys.IncorrectKeyOrder
+
+        return $locale;
+    }
+
+    /**
+     * Modifies the locale field selectors
+     *
+     * @param  array<string,string> $selectors Field selectors.
+     * @return array<string,string>
+     */
+    #[Filter( tag: 'woocommerce_country_locale_field_selectors', priority: 99999 )]
+    public function locale_field_selectors( array $selectors ): array {
+        return \array_merge(
+            $selectors,
+            array(
+                'company' => '#billing_company_field',
+                'mb'      => '#billing_mb_field',
+                'pib'     => '#billing_pib_field',
+                'type'    => '#billing_type_field',
+            ),
+        );
+    }
+
+    /**
+     * Modifies the billing fields to add the customer type and additional company fields
+     *
+     * @param  array $fields Billing fields.
+     * @return array         Modified billing fields
+     */
+    #[Filter( tag: 'woocommerce_shipping_fields', priority: 'woocommerce_serbian_checkout_fields_priority' )]
+    public function modify_shipping_fields( array $fields ) {
+        $to_remove = array( 'company', 'mb', 'pib', 'type' );
+
+        return \xwp_array_diff_assoc(
+            $fields,
+            ...\array_map( static fn( $f ) => "shipping_{$f}", $to_remove ),
+        );
+    }
+}
diff --git a/lib/Core/Address_Validate_Controller.php b/lib/Core/Address_Validate_Controller.php
new file mode 100644
index 0000000..b5bc13b
--- /dev/null
+++ b/lib/Core/Address_Validate_Controller.php
@@ -0,0 +1,47 @@
+<?php
+/**
+ * Address_Field_Controller class file.
+ *
+ * @package Serbian Addons for WooCommerce
+ */
+
+namespace Oblak\WCSRB\Core;
+
+use Oblak\WP\Abstracts\Hook_Caller;
+use Oblak\WP\Decorators\Action;
+use Oblak\WP\Decorators\Hookable;
+
+/**
+ * Changes the fields on the checkout page
+ *
+ * @since 3.8.0
+ */
+#[Hookable( 'woocommerce_init', 99 )]
+class Address_Validate_Controller extends Hook_Caller {
+    /**
+     * Validates the saved address.
+     *
+     * @param  int    $user_id User ID.
+     * @param  string $type    Address type being edited - billing or shipping.
+     */
+    #[Action( tag: 'woocommerce_after_save_address_validation', priority: 99 )]
+    public function validate_save_address( int $user_id, string $type ) {
+        foreach ( \WCSRB()->validator()->validate_fields( \xwp_post_arr(), $type ) as $error ) {
+            \wc_add_notice( $error['message'], 'error', array( 'id' => $error['id'] ) );
+        }
+    }
+
+
+    /**
+     * Validates the checkout fields.
+     *
+     * @param  array<string,array> $fields Address fields.
+     * @param  \WP_Error           $error  Error object.
+     */
+    #[Action( 'woocommerce_after_checkout_validation', 0 )]
+    public function validate_checkout( array $fields, \WP_Error $error ) {
+        foreach ( \WCSRB()->validator()->validate_fields( $fields, 'billing' ) as $err ) {
+            $error->add( $err['code'], $err['message'], array( 'id' => $err['id'] ) );
+        }
+    }
+}
diff --git a/lib/Functions/wcsrb-address-field-fns.php b/lib/Functions/wcsrb-address-field-fns.php
new file mode 100644
index 0000000..0cca998
--- /dev/null
+++ b/lib/Functions/wcsrb-address-field-fns.php
@@ -0,0 +1,96 @@
+<?php
+/**
+ * Address field functions.
+ *
+ * @package Serbian Addons for WooCommerce
+ */
+
+/**
+ * Gets the company address fields.
+ *
+ * @return array
+ *
+ * @since 3.8.0
+ */
+function wcsrb_get_company_fields(): array {
+    $fields = array(
+        'mb'  => array(
+            'class'       => array( 'form-row-first', 'address-field', 'entity-type-toggle', 'shown' ),
+            'label'       => \__( 'Company Number', 'serbian-addons-for-woocommerce' ),
+            'placeholder' => \__( 'Enter MB', 'serbian-addons-for-woocommerce' ),
+            'priority'    => 31,
+            'type'        => 'text',
+            'validate'    => array( 'mb' ),
+        ),
+        'pib' => array(
+            'class'       => array( 'form-row-last', 'address-field', 'entity-type-toggle', 'shown' ),
+            'label'       => \__( 'Tax Number', 'serbian-addons-for-woocommerce' ),
+            'placeholder' => \__( 'Enter PIB', 'serbian-addons-for-woocommerce' ),
+            'priority'    => 32,
+            'type'        => 'text',
+            'validate'    => array( 'pib' ),
+        ),
+    );
+
+    /**
+     * Filters the company address fields.
+     *
+     * @param  array $fields Company address fields.
+     * @return array
+     *
+     * @since 3.8.0
+     */
+    return apply_filters( 'wcsrb_company_address_fields', $fields );
+}
+
+/**
+ * Checks if the customer can checkout as a given type.
+ *
+ * @param  'person'|'company'|'both' $type Customer type.
+ * @return bool
+ */
+function wcsrb_can_checkout_as( string $type ): bool {
+    static $types;
+
+    $types ??= WCSRB()->get_settings( 'core', 'enabled_customer_types' );
+
+    return 'both' === $types || $type === $types;
+}
+
+
+/**
+ * Get the customer type for the given customer.
+ *
+ * @param  WC_Order|WC_Customer $target Customer ID or object.
+ * @return 'person'|'company'
+ */
+function wcsrb_get_customer_type( WC_Order|WC_Customer $target ): string {
+    $key = $target instanceof WC_Order ? '_billing_type' : 'billing_type';
+
+    // phpcs:ignore Universal
+    return $target->get_meta( $key, true ) ?: 'person';
+}
+
+/**
+ * Get the company data for the given customer.
+ *
+ * @param  WC_Order|WC_Customer $target Customer ID or object.
+ * @return false|array{mb: string, pib: string, type: 'company'|'person'}
+ */
+function wcsrb_get_company_data( WC_Order|WC_Customer $target ): bool|array {
+    if ( 'company' !== wcsrb_get_customer_type( $target ) ) {
+        return array(
+            'mb'   => '',
+            'pib'  => '',
+            'type' => 'person',
+        );
+    }
+
+    $key = $target instanceof WC_Order ? '_billing' : 'billing';
+
+    return array(
+        'mb'   => $target->get_meta( "{$key}_mb", true ),
+        'pib'  => $target->get_meta( "{$key}_pib", true ),
+        'type' => 'company',
+    );
+}
diff --git a/lib/Utils/wcsrb-core.php b/lib/Functions/wcsrb-core.php
similarity index 89%
rename from lib/Utils/wcsrb-core.php
rename to lib/Functions/wcsrb-core.php
index d7c583f..2ead635 100644
--- a/lib/Utils/wcsrb-core.php
+++ b/lib/Functions/wcsrb-core.php
@@ -6,15 +6,13 @@
  * @subpackage Utils
  */
 
-use Oblak\WooCommerce\Serbian_Addons\Serbian_WooCommerce;
-
 /**
  * Main Plugin Instance
  *
- * @return Serbian_WooCommerce
+ * @return Oblak\WCSRB\App
  */
 function WCSRB() {
-    return Serbian_WooCommerce::instance();
+    return Oblak\WCSRB\App::instance();
 }
 
 /**
diff --git a/lib/Utils/wcsrb-helpers.php b/lib/Functions/wcsrb-helpers.php
similarity index 100%
rename from lib/Utils/wcsrb-helpers.php
rename to lib/Functions/wcsrb-helpers.php
diff --git a/lib/Utils/wcsrb-payment-slip.php b/lib/Functions/wcsrb-payment-slip.php
similarity index 100%
rename from lib/Utils/wcsrb-payment-slip.php
rename to lib/Functions/wcsrb-payment-slip.php
diff --git a/lib/Utils/wcsrb-settings.php b/lib/Functions/wcsrb-settings.php
similarity index 100%
rename from lib/Utils/wcsrb-settings.php
rename to lib/Functions/wcsrb-settings.php
diff --git a/lib/Order/Field_Display.php b/lib/Order/Field_Display.php
deleted file mode 100644
index fe6bdb6..0000000
--- a/lib/Order/Field_Display.php
+++ /dev/null
@@ -1,200 +0,0 @@
-<?php
-/**
- * Field_Display class file.
- *
- * @package Serbian Addons for WooCommerce
- * @subpackage WooCommerce\Order
- */
-
-namespace Oblak\WooCommerce\Serbian_Addons\Order;
-
-use Oblak\WP\Abstracts\Hook_Caller;
-use Oblak\WP\Decorators\Filter;
-use Oblak\WP\Decorators\Hookable;
-use WC_Customer;
-use WC_Order;
-
-/**
- * Handles the address display customizations for orders and addresses
- */
-#[Hookable( 'woocommerce_init', 99 )]
-class Field_Display extends Hook_Caller {
-    /**
-     * Modifies the address format for Serbia to include necessary company information
-     *
-     * @param  string[] $formats Address formats.
-     * @return string[]          Modified address formats
-     */
-    #[Filter( 'woocommerce_localisation_address_formats', 'wcrs_localization_address_priority' )]
-    public function modify_address_format( $formats ) {
-        \add_filter( 'woocommerce_formatted_address_force_country_display', '__return_true' );
-
-        $formats['RS'] = "{name}\n{company}\n{mb}\n{pib}\n{address_1}\n{address_2}\n{postcode} {city}, {state} {country}";
-
-        if ( \WCSRB()->get_settings( 'core', 'remove_unneeded_fields' ) ) {
-            $formats['RS'] = \str_replace( array( '{state}', '{address_2}' ), '', $formats['RS'] );
-        }
-
-        return $formats;
-    }
-
-    /**
-     * Adds custom replacements to the replacements array.
-     *
-     * Custom fields added are:
-     *  - Type
-     *  - Company Number
-     *  - Tax Identification Number
-     *
-     * @param  string[] $replacements  Replacements array.
-     * @param  array    $args          Address data.
-     * @return string[]                Modified replacements array
-     */
-    #[Filter( 'woocommerce_formatted_address_replacements', 99 )]
-    public function modify_address_replacements( $replacements, $args ) {
-        $replacements['{type}'] = $args['type'] ?? "\n";
-        $replacements['{mb}']   = $args['mb'] ?? "\n";
-        $replacements['{pib}']  = $args['pib'] ?? "\n";
-
-        return $replacements;
-    }
-
-    /**
-     * Modifies the address data array to include neccecary company information.
-     *
-     * This is used in the My Account > Addresses page.
-     *
-     * @param  array  $address      Address data array.
-     * @param  int    $customer_id  Customer ID.
-     * @param  string $address_type Address type (billing or shipping).
-     * @return array                Modified address data array
-     */
-    #[Filter( 'woocommerce_my_account_my_address_formatted_address', 99 )]
-    public function modify_account_formatted_address( $address, $customer_id, $address_type ) {
-        if ( 'billing' !== $address_type ) {
-            return $address;
-        }
-
-        $customer = new WC_Customer( $customer_id );
-
-        // phpcs:ignore Universal.Operators.DisallowShortTernary.Found
-        $user_type   = $customer->get_meta( 'billing_type', true ) ?: 'person';
-        $company_num = $customer->get_meta( 'billing_mb', true );
-        $company_tax = $customer->get_meta( 'billing_pib', true );
-
-        return $this->address_modifier( $address, $user_type, $company_num, $company_tax );
-    }
-
-    /**
-     * Modifies the address data array to include neccecary company information.
-     *
-     * This is used for the order addresses.
-     *
-     * @param  array    $address Address data array.
-     * @param  WC_Order $order   Order object.
-     * @return array             Modified address data array
-     */
-    #[Filter( 'woocommerce_order_formatted_billing_address', 99 )]
-    public function modify_order_formatted_address( $address, $order ) {
-        return $this->address_modifier(
-            $address,
-            $order->get_meta( '_billing_type', true ),
-            $order->get_meta( '_billing_mb', true ),
-            $order->get_meta( '_billing_pib', true ),
-        );
-    }
-
-    /**
-     * Billing address modifier function
-     *
-     * Depending on the customer(user) type we add the needed rows to the address.
-     * If the customer is a company we prepend the number type before the number itself
-     *
-     * @param  array  $address        Billing address data array.
-     * @param  string $type           User type (person or company).
-     * @param  string $company_number Company number.
-     * @param  string $tax_number     Company tax number.
-     * @return array                  Modified billing address data array.
-     */
-    private function address_modifier( $address, $type, $company_number, $tax_number ) {
-        $address['type'] = $type;
-        $address['mb']   = "\n";
-        $address['pib']  = "\n";
-
-        if ( 'company' !== $type ) {
-            return $address;
-        }
-
-        $address['first_name'] = "\n";
-        $address['last_name']  = "\n";
-
-        if ( $company_number ) {
-            $address['mb'] = \sprintf(
-                '%s: %s',
-                \_x( 'Company Number', 'Address display', 'serbian-addons-for-woocommerce' ),
-                $company_number,
-            );
-        }
-        $address['pib'] = \sprintf(
-            '%s: %s',
-            \_x( 'Tax Identification Number', 'Address display', 'serbian-addons-for-woocommerce' ),
-            $tax_number,
-        );
-
-        return $address;
-    }
-
-    /**
-     * Modifies the buyer name in the admin order page to include necessary company information
-     *
-     * @param  string   $buyer Buyer name.
-     * @param  WC_Order $order Order object.
-     * @return string          Modified Buyer name
-     */
-    #[Filter( 'woocommerce_admin_order_buyer_name', 99 )]
-    public function modify_order_buyer_name( $buyer, $order ) {
-        return 'RS' === $order->get_billing_country() && 'company' === $order->get_meta( '_billing_type', true )
-            ? $order->get_billing_company()
-            : $buyer;
-    }
-
-    /**
-     * Adds the company information to the customer meta fields.
-     *
-     * @param  array $fields Customer meta fields.
-     * @return array         Modified customer meta fields
-     */
-    #[Filter( 'woocommerce_customer_meta_fields' )]
-    public function modify_customer_meta_fields( array $fields ): array {
-        $billing = array();
-
-        foreach ( $fields['billing']['fields'] as $field => $args ) {
-            if ( 'billing_company' !== $field ) {
-                $billing[ $field ] = $args;
-                continue;
-            }
-
-            $billing['billing_type'] = array(
-                'label'   => \__( 'Customer type', 'serbian-addons-for-woocommerce' ),
-                'options' => \wcsrb_get_entity_types(),
-                'type'    => 'select',
-            );
-
-            $billing[ $field ] = $args;
-
-            $billing['billing_mb'] = array(
-                'label' => \__( 'Company Number', 'serbian-addons-for-woocommerce' ),
-                'type'  => 'text',
-            );
-
-            $billing['billing_pib'] = array(
-                'label' => \__( 'Tax Number', 'serbian-addons-for-woocommerce' ),
-                'type'  => 'text',
-            );
-        }
-
-        $fields['billing']['fields'] = $billing;
-
-        return $fields;
-    }
-}
diff --git a/lib/Services/Field_Validator.php b/lib/Services/Field_Validator.php
new file mode 100644
index 0000000..63dca2a
--- /dev/null
+++ b/lib/Services/Field_Validator.php
@@ -0,0 +1,141 @@
+<?php
+/**
+ * Field_Validator class file.
+ *
+ * @package Serbian Addons for WooCommerce
+ */
+
+namespace Oblak\WCSRB\Services;
+
+/**
+ * Validates the address fields.
+ *
+ * @since 3.8.0
+ */
+class Field_Validator {
+    /**
+     * Whether the company checkout is active.
+     *
+     * @var bool
+     */
+    private bool $company_active;
+
+    /**
+     * Constructor
+     */
+    public function __construct() {
+        $this->company_active = \wcsrb_can_checkout_as( 'company' );
+    }
+
+    /**
+     * Validates the address fields.
+     *
+     * @param  array<string,array>  $fields Address fields.
+     * @param  'billing'|'shipping' $type   Address type being validated.
+     * @param  array<string,array>  $address Address fields.
+     * @return null|array<int, array{
+     *   code: string,
+     *   id: string,
+     *   message: string,
+     * }>
+     */
+    public function validate_fields( array $fields, string $type, ?array $address = null ): array {
+        if ( ! $this->needs_validation( $fields ) ) {
+            return array();
+        }
+
+        $address ??= \WC()->countries->get_address_fields( $fields[ "{$type}_country" ], $type . '_' );
+        $errors    = array();
+
+        foreach ( $this->get_field_validators() as $key => $args ) {
+            $errors[] = $this->validate_field( $fields[ $key ] ?? '', $key, $args, $address[ $key ] );
+
+        }
+
+        //phpcs:ignore Universal.Operators.DisallowShortTernary.Found
+        return \array_filter( $errors );
+    }
+
+    /**
+     * Validates the given field.
+     *
+     * @param  mixed  $value Field value.
+     * @param  string $key   Field key.
+     * @param  array  $args  Validation arguments.
+     * @param  array  $field Field data.
+     * @return ?array        Error data if validation fails, null otherwise.
+     */
+    protected function validate_field( mixed $value, string $key, array $args, array $field ): ?array {
+        if ( ! $value ) {
+            return array(
+                'code'    => "{$key}_required",
+                'id'      => $key,
+                // Translators: %s: Field label.
+                'message' => \sprintf( \__( '%s is a required field.', 'woocommerce' ), $field['label'] ),
+            );
+        }
+
+        if ( ! $args['callback']( $value ) ) {
+            return array(
+                'code'    => $args['code'],
+                'id'      => $key,
+                'message' => $args['message'],
+            );
+        }
+
+        return null;
+    }
+
+    /**
+     * Returns the field validators for the given action.
+     *
+     * @return array<string, array{
+     *   code: string,
+     *   message: string,
+     *   callback: callable,
+     * }>
+     */
+    protected function get_field_validators(): array {
+        $args = array(
+            'billing_company' => array(
+                'callback' => '__return_true',
+                'code'     => 'billing_company_required',
+                'message'  => \__( 'Company name is required', 'serbian-addons-for-woocommerce' ),
+            ),
+            'billing_mb'      => array(
+                'callback' => '\Oblak\validateMB',
+                'code'     => 'billing_mb_validation',
+                'message'  => \__( 'Company number is invalid', 'serbian-addons-for-woocommerce' ),
+            ),
+            'billing_pib'     => array(
+                'callback' => '\Oblak\validatePIB',
+                'code'     => 'billing_pib_validation',
+                'message'  => \__( 'Company Tax Number is invalid', 'serbian-addons-for-woocommerce' ),
+            ),
+        );
+
+        /**
+         * Returns the validation arguments for the given action.
+         *
+         * @param  array  $args   Validation arguments.
+         * @return array
+         *
+         * @since 3.6.0
+         */
+        return \apply_filters( 'wcrs_field_validators', $args );
+    }
+
+    /**
+     * Checks if the current address can be validated.
+     *
+     * @param  array<string,array>  $fields  Address fields.
+     * @param  'billing'|'shipping' $address Address type being validated.
+     * @return bool
+     */
+    protected function needs_validation( array $fields, string $address = 'billing' ): bool {
+        return $this->company_active &&
+            'billing' === $address &&
+            'company' === ( $fields['billing_type'] ?? '' ) &&
+            'RS' === ( $fields['billing_country'] ?? '' );
+    }
+}
diff --git a/lib/Core/Installer.php b/lib/Utils/Installer.php
similarity index 98%
rename from lib/Core/Installer.php
rename to lib/Utils/Installer.php
index 4909221..54a607d 100644
--- a/lib/Core/Installer.php
+++ b/lib/Utils/Installer.php
@@ -6,7 +6,7 @@
  * @subpackage Core
  */
 
-namespace Oblak\WooCommerce\Serbian_Addons\Core;
+namespace Oblak\WCSRB\Utils;
 
 use Oblak\WP\Base_Plugin_Installer;
 
diff --git a/lib/Core/Template_Extender.php b/lib/Utils/Template_Extender.php
similarity index 91%
rename from lib/Core/Template_Extender.php
rename to lib/Utils/Template_Extender.php
index 068692d..0610699 100644
--- a/lib/Core/Template_Extender.php
+++ b/lib/Utils/Template_Extender.php
@@ -5,7 +5,7 @@
  * @package Serbian Addons for WooCommerce
  */
 
-namespace Oblak\WooCommerce\Serbian_Addons\Core;
+namespace Oblak\WCSRB\Utils;
 
 use Oblak\WP\Decorators\Hookable;
 use XWC\Template\Customizer_Base;
@@ -14,6 +14,7 @@
  * Adds custom templates to WooCommerce.
  *
  * @since 2.3.0
+ * @since 3.8.0 Moved from the `Core` namespace.
  */
 #[Hookable( 'before_woocommerce_init', 99 )]
 class Template_Extender extends Customizer_Base {