diff --git a/codegen/internal/generator/model.go b/codegen/internal/generator/model.go
index 184fd51..74f43ea 100644
--- a/codegen/internal/generator/model.go
+++ b/codegen/internal/generator/model.go
@@ -98,6 +98,7 @@ type schemaField struct {
 	Type             string
 	DescriptionLines []string
 	Required         bool
+	ReadOnly         bool
 }
 
 // enumValueModel captures a single enum constant and its wire value.
@@ -583,6 +584,7 @@ func buildSchemaFields(name string, ref *base.SchemaProxy, resolver *typeResolve
 			for _, imp := range javaType.Imports {
 				imports[imp] = struct{}{}
 			}
+			readOnly := isReadOnlySchema(propRef)
 			desc := ""
 			if schemaFromProxy(propRef) != nil {
 				desc = schemaFromProxy(propRef).Description
@@ -592,8 +594,9 @@ func buildSchemaFields(name string, ref *base.SchemaProxy, resolver *typeResolve
 				Type:             javaType.Name,
 				DescriptionLines: splitComment(desc),
 				Required:         required[propName],
+				ReadOnly:         readOnly,
 			})
-			if required[propName] {
+			if required[propName] && !readOnly {
 				hasRequired = true
 			}
 		}
@@ -737,6 +740,12 @@ func schemaHasType(schema *base.Schema, want string) bool {
 	return false
 }
 
+// isReadOnlySchema reports whether the schema marks this value as readOnly.
+func isReadOnlySchema(proxy *base.SchemaProxy) bool {
+	schema := schemaFromProxy(proxy)
+	return schema != nil && schema.ReadOnly != nil && *schema.ReadOnly
+}
+
 // sortedImports deterministically orders import strings so rendered files do
 // not churn between runs.
 func sortedImports(set map[string]struct{}) []string {
diff --git a/codegen/internal/generator/templates/model.tmpl b/codegen/internal/generator/templates/model.tmpl
index 5737414..7c81fcb 100644
--- a/codegen/internal/generator/templates/model.tmpl
+++ b/codegen/internal/generator/templates/model.tmpl
@@ -77,8 +77,10 @@ public record {{ .ClassName }}(
     public static final class Builder {
 {{- if .Fields }}
 {{- range .Fields }}
+{{- if not .ReadOnly }}
         private {{ .Type }} {{ .Name }};
 {{- end }}
+{{- end }}
 {{- else }}
         private Object value;
 {{- end }}
@@ -87,6 +89,7 @@ public record {{ .ClassName }}(
 
 {{- if .Fields }}
 {{- range .Fields }}
+{{- if not .ReadOnly }}
         /**
          * Sets the value for {@code {{ .Name }}}.
          *
@@ -98,6 +101,7 @@ public record {{ .ClassName }}(
             return this;
         }
 {{- end }}
+{{- end }}
 {{- else }}
         /**
          * Sets the wrapped value field.
@@ -121,7 +125,7 @@ public record {{ .ClassName }}(
             return new {{ $.ClassName }}(
 {{- range $index, $field := .Fields }}
 {{- if $index }},
-{{ end }}                {{ if $field.Required }}Objects.requireNonNull({{ $field.Name }}, {{ quote $field.Name }}){{ else }}{{ $field.Name }}{{ end }}
+{{ end }}                {{ if $field.ReadOnly }}null{{ else if $field.Required }}Objects.requireNonNull({{ $field.Name }}, {{ quote $field.Name }}){{ else }}{{ $field.Name }}{{ end }}
 {{- end }}
             );
 {{- else }}
diff --git a/src/main/java/com/sumup/sdk/models/BasePerson.java b/src/main/java/com/sumup/sdk/models/BasePerson.java
index b02cee0..0cefdd9 100644
--- a/src/main/java/com/sumup/sdk/models/BasePerson.java
+++ b/src/main/java/com/sumup/sdk/models/BasePerson.java
@@ -1,8 +1,6 @@
 // Code generated by sumup-java/codegen. DO NOT EDIT.
 package com.sumup.sdk.models;
 
-import java.util.Objects;
-
 /**
  * Base schema for a person associated with a merchant. This can be a legal representative, business
  * owner (ultimate beneficial owner), or an officer. A legal representative is the person who
@@ -104,12 +102,10 @@ public static Builder builder() {
   public static final class Builder {
     private com.sumup.sdk.models.Address address;
     private java.time.LocalDate birthdate;
-    private com.sumup.sdk.models.ChangeStatus changeStatus;
     private com.sumup.sdk.models.CountryCode citizenship;
     private String countryOfResidence;
     private String familyName;
     private String givenName;
-    private String id;
     private java.util.List<com.sumup.sdk.models.PersonalIdentifier> identifiers;
     private String middleName;
     private String nationality;
@@ -148,21 +144,6 @@ public Builder birthdate(java.time.LocalDate birthdate) {
       return this;
     }
 
-    /**
-     * Sets the value for {@code changeStatus}.
-     *
-     * @param changeStatus Reflects the status of changes submitted through the `PATCH` endpoints
-     *     for the merchant or persons. If some changes have not been applied yet, the status will
-     *     be `pending`. If all changes have been applied, the status `done`. The status is only
-     *     returned after write operations or on read endpoints when the `version` query parameter
-     *     is provided.
-     * @return This builder instance.
-     */
-    public Builder changeStatus(com.sumup.sdk.models.ChangeStatus changeStatus) {
-      this.changeStatus = changeStatus;
-      return this;
-    }
-
     /**
      * Sets the value for {@code citizenship}.
      *
@@ -211,18 +192,6 @@ public Builder givenName(String givenName) {
       return this;
     }
 
-    /**
-     * Sets the value for {@code id}.
-     *
-     * @param id The unique identifier for the person. This is a
-     *     [typeid](https://github.com/sumup/typeid).
-     * @return This builder instance.
-     */
-    public Builder id(String id) {
-      this.id = id;
-      return this;
-    }
-
     /**
      * Sets the value for {@code identifiers}.
      *
@@ -328,12 +297,12 @@ public BasePerson build() {
       return new BasePerson(
           address,
           birthdate,
-          changeStatus,
+          null,
           citizenship,
           countryOfResidence,
           familyName,
           givenName,
-          Objects.requireNonNull(id, "id"),
+          null,
           identifiers,
           middleName,
           nationality,
diff --git a/src/main/java/com/sumup/sdk/models/Card.java b/src/main/java/com/sumup/sdk/models/Card.java
index ac6d690..b4c7787 100644
--- a/src/main/java/com/sumup/sdk/models/Card.java
+++ b/src/main/java/com/sumup/sdk/models/Card.java
@@ -42,7 +42,6 @@ public static final class Builder {
     private String cvv;
     private com.sumup.sdk.models.CardExpiryMonth expiryMonth;
     private String expiryYear;
-    private String last4Digits;
     private String name;
     private String number;
     private com.sumup.sdk.models.CardType type;
@@ -85,17 +84,6 @@ public Builder expiryYear(String expiryYear) {
       return this;
     }
 
-    /**
-     * Sets the value for {@code last4Digits}.
-     *
-     * @param last4Digits Last 4 digits of the payment card number.
-     * @return This builder instance.
-     */
-    public Builder last4Digits(String last4Digits) {
-      this.last4Digits = last4Digits;
-      return this;
-    }
-
     /**
      * Sets the value for {@code name}.
      *
@@ -150,7 +138,7 @@ public Card build() {
           Objects.requireNonNull(cvv, "cvv"),
           Objects.requireNonNull(expiryMonth, "expiryMonth"),
           Objects.requireNonNull(expiryYear, "expiryYear"),
-          Objects.requireNonNull(last4Digits, "last4Digits"),
+          null,
           Objects.requireNonNull(name, "name"),
           Objects.requireNonNull(number, "number"),
           Objects.requireNonNull(type, "type"),
diff --git a/src/main/java/com/sumup/sdk/models/CardResponse.java b/src/main/java/com/sumup/sdk/models/CardResponse.java
index eafcb46..47ee1ac 100644
--- a/src/main/java/com/sumup/sdk/models/CardResponse.java
+++ b/src/main/java/com/sumup/sdk/models/CardResponse.java
@@ -19,22 +19,10 @@ public static Builder builder() {
 
   /** Builder for CardResponse instances. */
   public static final class Builder {
-    private String last4Digits;
     private com.sumup.sdk.models.CardType type;
 
     private Builder() {}
 
-    /**
-     * Sets the value for {@code last4Digits}.
-     *
-     * @param last4Digits Last 4 digits of the payment card number.
-     * @return This builder instance.
-     */
-    public Builder last4Digits(String last4Digits) {
-      this.last4Digits = last4Digits;
-      return this;
-    }
-
     /**
      * Sets the value for {@code type}.
      *
@@ -52,7 +40,7 @@ public Builder type(com.sumup.sdk.models.CardType type) {
      * @return Immutable CardResponse.
      */
     public CardResponse build() {
-      return new CardResponse(last4Digits, type);
+      return new CardResponse(null, type);
     }
   }
 }
diff --git a/src/main/java/com/sumup/sdk/models/Checkout.java b/src/main/java/com/sumup/sdk/models/Checkout.java
index 2ce0a64..9d39c66 100644
--- a/src/main/java/com/sumup/sdk/models/Checkout.java
+++ b/src/main/java/com/sumup/sdk/models/Checkout.java
@@ -76,7 +76,6 @@ public static final class Builder {
     private String customerId;
     private java.time.OffsetDateTime date;
     private String description;
-    private String id;
     private com.sumup.sdk.models.MandateResponse mandate;
     private String merchantCode;
     private String returnUrl;
@@ -157,17 +156,6 @@ public Builder description(String description) {
       return this;
     }
 
-    /**
-     * Sets the value for {@code id}.
-     *
-     * @param id Unique ID of the checkout resource.
-     * @return This builder instance.
-     */
-    public Builder id(String id) {
-      this.id = id;
-      return this;
-    }
-
     /**
      * Sets the value for {@code mandate}.
      *
@@ -250,7 +238,7 @@ public Checkout build() {
           customerId,
           date,
           description,
-          id,
+          null,
           mandate,
           merchantCode,
           returnUrl,
diff --git a/src/main/java/com/sumup/sdk/models/CheckoutCreateRequest.java b/src/main/java/com/sumup/sdk/models/CheckoutCreateRequest.java
index bb94d70..eea8522 100644
--- a/src/main/java/com/sumup/sdk/models/CheckoutCreateRequest.java
+++ b/src/main/java/com/sumup/sdk/models/CheckoutCreateRequest.java
@@ -86,15 +86,11 @@ public static final class Builder {
     private String checkoutReference;
     private com.sumup.sdk.models.Currency currency;
     private String customerId;
-    private java.time.OffsetDateTime date;
     private String description;
-    private String id;
     private String merchantCode;
     private com.sumup.sdk.models.CheckoutCreateRequestPurpose purpose;
     private String redirectUrl;
     private String returnUrl;
-    private com.sumup.sdk.models.CheckoutCreateRequestStatus status;
-    private java.util.List<com.sumup.sdk.models.TransactionBase> transactions;
     private java.time.OffsetDateTime validUntil;
 
     private Builder() {}
@@ -146,18 +142,6 @@ public Builder customerId(String customerId) {
       return this;
     }
 
-    /**
-     * Sets the value for {@code date}.
-     *
-     * @param date Date and time of the creation of the payment checkout. Response format expressed
-     *     according to [ISO8601](https://en.wikipedia.org/wiki/ISO_8601) code.
-     * @return This builder instance.
-     */
-    public Builder date(java.time.OffsetDateTime date) {
-      this.date = date;
-      return this;
-    }
-
     /**
      * Sets the value for {@code description}.
      *
@@ -170,17 +154,6 @@ public Builder description(String description) {
       return this;
     }
 
-    /**
-     * Sets the value for {@code id}.
-     *
-     * @param id Unique ID of the checkout resource.
-     * @return This builder instance.
-     */
-    public Builder id(String id) {
-      this.id = id;
-      return this;
-    }
-
     /**
      * Sets the value for {@code merchantCode}.
      *
@@ -232,28 +205,6 @@ public Builder returnUrl(String returnUrl) {
       return this;
     }
 
-    /**
-     * Sets the value for {@code status}.
-     *
-     * @param status Current status of the checkout.
-     * @return This builder instance.
-     */
-    public Builder status(com.sumup.sdk.models.CheckoutCreateRequestStatus status) {
-      this.status = status;
-      return this;
-    }
-
-    /**
-     * Sets the value for {@code transactions}.
-     *
-     * @param transactions List of transactions related to the payment.
-     * @return This builder instance.
-     */
-    public Builder transactions(java.util.List<com.sumup.sdk.models.TransactionBase> transactions) {
-      this.transactions = transactions;
-      return this;
-    }
-
     /**
      * Sets the value for {@code validUntil}.
      *
@@ -278,15 +229,15 @@ public CheckoutCreateRequest build() {
           Objects.requireNonNull(checkoutReference, "checkoutReference"),
           Objects.requireNonNull(currency, "currency"),
           customerId,
-          date,
+          null,
           description,
-          id,
+          null,
           Objects.requireNonNull(merchantCode, "merchantCode"),
           purpose,
           redirectUrl,
           returnUrl,
-          status,
-          transactions,
+          null,
+          null,
           validUntil);
     }
   }
diff --git a/src/main/java/com/sumup/sdk/models/Merchant2.java b/src/main/java/com/sumup/sdk/models/Merchant2.java
index 20b22b8..4e2d0a9 100644
--- a/src/main/java/com/sumup/sdk/models/Merchant2.java
+++ b/src/main/java/com/sumup/sdk/models/Merchant2.java
@@ -107,13 +107,10 @@ public static final class Builder {
     private String avatar;
     private com.sumup.sdk.models.BusinessProfile businessProfile;
     private String businessType;
-    private com.sumup.sdk.models.ChangeStatus changeStatus;
     private com.sumup.sdk.models.ClassicMerchantIdentifiers classic;
     private com.sumup.sdk.models.Company company;
     private com.sumup.sdk.models.CountryCode country;
-    private String defaultCurrency;
     private String defaultLocale;
-    private String merchantCode;
     private com.sumup.sdk.models.Meta meta;
     private String organizationId;
     private Boolean sandbox;
@@ -174,21 +171,6 @@ public Builder businessType(String businessType) {
       return this;
     }
 
-    /**
-     * Sets the value for {@code changeStatus}.
-     *
-     * @param changeStatus Reflects the status of changes submitted through the `PATCH` endpoints
-     *     for the merchant or persons. If some changes have not been applied yet, the status will
-     *     be `pending`. If all changes have been applied, the status `done`. The status is only
-     *     returned after write operations or on read endpoints when the `version` query parameter
-     *     is provided.
-     * @return This builder instance.
-     */
-    public Builder changeStatus(com.sumup.sdk.models.ChangeStatus changeStatus) {
-      this.changeStatus = changeStatus;
-      return this;
-    }
-
     /**
      * Sets the value for {@code classic}.
      *
@@ -225,19 +207,6 @@ public Builder country(com.sumup.sdk.models.CountryCode country) {
       return this;
     }
 
-    /**
-     * Sets the value for {@code defaultCurrency}.
-     *
-     * @param defaultCurrency Three-letter [ISO currency
-     *     code](https://en.wikipedia.org/wiki/ISO_4217) representing the default currency for the
-     *     account.
-     * @return This builder instance.
-     */
-    public Builder defaultCurrency(String defaultCurrency) {
-      this.defaultCurrency = defaultCurrency;
-      return this;
-    }
-
     /**
      * Sets the value for {@code defaultLocale}.
      *
@@ -256,17 +225,6 @@ public Builder defaultLocale(String defaultLocale) {
       return this;
     }
 
-    /**
-     * Sets the value for {@code merchantCode}.
-     *
-     * @param merchantCode Short unique identifier for the merchant.
-     * @return This builder instance.
-     */
-    public Builder merchantCode(String merchantCode) {
-      this.merchantCode = merchantCode;
-      return this;
-    }
-
     /**
      * Sets the value for {@code meta}.
      *
@@ -326,13 +284,13 @@ public Merchant2 build() {
           avatar,
           businessProfile,
           businessType,
-          changeStatus,
+          null,
           classic,
           company,
           Objects.requireNonNull(country, "country"),
-          Objects.requireNonNull(defaultCurrency, "defaultCurrency"),
+          null,
           Objects.requireNonNull(defaultLocale, "defaultLocale"),
-          Objects.requireNonNull(merchantCode, "merchantCode"),
+          null,
           meta,
           organizationId,
           sandbox,
diff --git a/src/main/java/com/sumup/sdk/models/PaymentInstrumentCard.java b/src/main/java/com/sumup/sdk/models/PaymentInstrumentCard.java
index 6c7fb55..e45fb74 100644
--- a/src/main/java/com/sumup/sdk/models/PaymentInstrumentCard.java
+++ b/src/main/java/com/sumup/sdk/models/PaymentInstrumentCard.java
@@ -30,25 +30,11 @@ public static Builder builder() {
 
   /** Builder for PaymentInstrumentCard instances. */
   public static final class Builder {
-    private Boolean active;
     private com.sumup.sdk.models.Card card;
-    private String token;
     private com.sumup.sdk.models.PaymentInstrumentCardType type;
 
     private Builder() {}
 
-    /**
-     * Sets the value for {@code active}.
-     *
-     * @param active Indicates whether the payment instrument is active and can be used for
-     *     payments. To deactivate it, send a `DELETE` request to the resource endpoint.
-     * @return This builder instance.
-     */
-    public Builder active(Boolean active) {
-      this.active = active;
-      return this;
-    }
-
     /**
      * Sets the value for {@code card}.
      *
@@ -60,17 +46,6 @@ public Builder card(com.sumup.sdk.models.Card card) {
       return this;
     }
 
-    /**
-     * Sets the value for {@code token}.
-     *
-     * @param token Unique token identifying the saved payment card for a customer.
-     * @return This builder instance.
-     */
-    public Builder token(String token) {
-      this.token = token;
-      return this;
-    }
-
     /**
      * Sets the value for {@code type}.
      *
@@ -89,10 +64,7 @@ public Builder type(com.sumup.sdk.models.PaymentInstrumentCardType type) {
      */
     public PaymentInstrumentCard build() {
       return new PaymentInstrumentCard(
-          Objects.requireNonNull(active, "active"),
-          Objects.requireNonNull(card, "card"),
-          Objects.requireNonNull(token, "token"),
-          Objects.requireNonNull(type, "type"));
+          null, Objects.requireNonNull(card, "card"), null, Objects.requireNonNull(type, "type"));
     }
   }
 }
diff --git a/src/main/java/com/sumup/sdk/models/PaymentInstrumentResponse.java b/src/main/java/com/sumup/sdk/models/PaymentInstrumentResponse.java
index f6765e8..8a42f0b 100644
--- a/src/main/java/com/sumup/sdk/models/PaymentInstrumentResponse.java
+++ b/src/main/java/com/sumup/sdk/models/PaymentInstrumentResponse.java
@@ -37,27 +37,13 @@ public static Builder builder() {
 
   /** Builder for PaymentInstrumentResponse instances. */
   public static final class Builder {
-    private Boolean active;
     private com.sumup.sdk.models.PaymentInstrumentResponseCard card;
     private java.time.OffsetDateTime createdAt;
     private com.sumup.sdk.models.MandateResponse mandate;
-    private String token;
     private com.sumup.sdk.models.PaymentInstrumentResponseType type;
 
     private Builder() {}
 
-    /**
-     * Sets the value for {@code active}.
-     *
-     * @param active Indicates whether the payment instrument is active and can be used for
-     *     payments. To deactivate it, send a `DELETE` request to the resource endpoint.
-     * @return This builder instance.
-     */
-    public Builder active(Boolean active) {
-      this.active = active;
-      return this;
-    }
-
     /**
      * Sets the value for {@code card}.
      *
@@ -92,17 +78,6 @@ public Builder mandate(com.sumup.sdk.models.MandateResponse mandate) {
       return this;
     }
 
-    /**
-     * Sets the value for {@code token}.
-     *
-     * @param token Unique token identifying the saved payment card for a customer.
-     * @return This builder instance.
-     */
-    public Builder token(String token) {
-      this.token = token;
-      return this;
-    }
-
     /**
      * Sets the value for {@code type}.
      *
@@ -120,7 +95,7 @@ public Builder type(com.sumup.sdk.models.PaymentInstrumentResponseType type) {
      * @return Immutable PaymentInstrumentResponse.
      */
     public PaymentInstrumentResponse build() {
-      return new PaymentInstrumentResponse(active, card, createdAt, mandate, token, type);
+      return new PaymentInstrumentResponse(null, card, createdAt, mandate, null, type);
     }
   }
 }
diff --git a/src/main/java/com/sumup/sdk/models/PaymentInstrumentResponseCard.java b/src/main/java/com/sumup/sdk/models/PaymentInstrumentResponseCard.java
index 7d16225..e3a03eb 100644
--- a/src/main/java/com/sumup/sdk/models/PaymentInstrumentResponseCard.java
+++ b/src/main/java/com/sumup/sdk/models/PaymentInstrumentResponseCard.java
@@ -19,22 +19,10 @@ public static Builder builder() {
 
   /** Builder for PaymentInstrumentResponseCard instances. */
   public static final class Builder {
-    private String last4Digits;
     private com.sumup.sdk.models.CardType type;
 
     private Builder() {}
 
-    /**
-     * Sets the value for {@code last4Digits}.
-     *
-     * @param last4Digits Last 4 digits of the payment card number.
-     * @return This builder instance.
-     */
-    public Builder last4Digits(String last4Digits) {
-      this.last4Digits = last4Digits;
-      return this;
-    }
-
     /**
      * Sets the value for {@code type}.
      *
@@ -52,7 +40,7 @@ public Builder type(com.sumup.sdk.models.CardType type) {
      * @return Immutable PaymentInstrumentResponseCard.
      */
     public PaymentInstrumentResponseCard build() {
-      return new PaymentInstrumentResponseCard(last4Digits, type);
+      return new PaymentInstrumentResponseCard(null, type);
     }
   }
 }
diff --git a/src/main/java/com/sumup/sdk/models/Timestamps.java b/src/main/java/com/sumup/sdk/models/Timestamps.java
index e009818..554806f 100644
--- a/src/main/java/com/sumup/sdk/models/Timestamps.java
+++ b/src/main/java/com/sumup/sdk/models/Timestamps.java
@@ -1,8 +1,6 @@
 // Code generated by sumup-java/codegen. DO NOT EDIT.
 package com.sumup.sdk.models;
 
-import java.util.Objects;
-
 public record Timestamps(
     /**
      * The date and time when the resource was created. This is a string as defined in [RFC 3339,
@@ -26,45 +24,16 @@ public static Builder builder() {
 
   /** Builder for Timestamps instances. */
   public static final class Builder {
-    private java.time.OffsetDateTime createdAt;
-    private java.time.OffsetDateTime updatedAt;
 
     private Builder() {}
 
-    /**
-     * Sets the value for {@code createdAt}.
-     *
-     * @param createdAt The date and time when the resource was created. This is a string as defined
-     *     in [RFC 3339, section 5.6](https://datatracker.ietf.org/doc/html/rfc3339#section-5.6).
-     * @return This builder instance.
-     */
-    public Builder createdAt(java.time.OffsetDateTime createdAt) {
-      this.createdAt = createdAt;
-      return this;
-    }
-
-    /**
-     * Sets the value for {@code updatedAt}.
-     *
-     * @param updatedAt The date and time when the resource was last updated. This is a string as
-     *     defined in [RFC 3339, section
-     *     5.6](https://datatracker.ietf.org/doc/html/rfc3339#section-5.6).
-     * @return This builder instance.
-     */
-    public Builder updatedAt(java.time.OffsetDateTime updatedAt) {
-      this.updatedAt = updatedAt;
-      return this;
-    }
-
     /**
      * Builds an immutable Timestamps instance.
      *
      * @return Immutable Timestamps.
      */
     public Timestamps build() {
-      return new Timestamps(
-          Objects.requireNonNull(createdAt, "createdAt"),
-          Objects.requireNonNull(updatedAt, "updatedAt"));
+      return new Timestamps(null, null);
     }
   }
 }