diff --git a/l10n_it_sct_cbi/models/account_payment_order.py b/l10n_it_sct_cbi/models/account_payment_order.py
index 70321b527662..9fae3d534467 100644
--- a/l10n_it_sct_cbi/models/account_payment_order.py
+++ b/l10n_it_sct_cbi/models/account_payment_order.py
@@ -349,7 +349,7 @@ def _l10n_it_sct_cbi_generate_transaction_block(
         payment_identification_CtgyPurp_Cd = etree.SubElement(
             payment_identification_CtgyPurp, "Cd"
         )
-        payment_identification_CtgyPurp_Cd.text = "SEPA"
+        payment_identification_CtgyPurp_Cd.text = "SUPP"
         instruction_identification = etree.SubElement(payment_identification, "InstrId")
         instruction_identification.text = self._prepare_field(
             "Instruction Identification",
diff --git a/l10n_it_sct_cbi/tests/test_generate_file.py b/l10n_it_sct_cbi/tests/test_generate_file.py
index cc350a31f4c4..c7df0d632d70 100644
--- a/l10n_it_sct_cbi/tests/test_generate_file.py
+++ b/l10n_it_sct_cbi/tests/test_generate_file.py
@@ -3,6 +3,8 @@
 
 import base64
 
+from lxml import etree
+
 from odoo import Command
 from odoo.tests import Form, tagged
 
@@ -105,9 +107,20 @@ def test_2_bills(self):
         payment_att = self._get_payment_attachment(bills)
 
         # Assert
-        payment_att_content = base64.b64decode(payment_att.datas).decode()
-        self.assertIn(bill_1.ref, payment_att_content)
-        self.assertIn(bill_2.ref, payment_att_content)
+        payment_tree = etree.fromstring(base64.b64decode(payment_att.datas))
+        namespaces = payment_tree.nsmap
+        bills_refs_node = payment_tree.find(
+            ".//PMRQ:RmtInf//PMRQ:Ustrd",
+            namespaces=namespaces,
+        )
+        self.assertIn(bill_1.ref, bills_refs_node.text)
+        self.assertIn(bill_2.ref, bills_refs_node.text)
+
+        category_purpose_code_node = payment_tree.find(
+            ".//PMRQ:CtgyPurp//PMRQ:Cd",
+            namespaces=namespaces,
+        )
+        self.assertEqual(category_purpose_code_node.text, "SUPP")
 
     def test_multiple_payment_priority(self):
         """Generate a payment file for a vendor bill
@@ -143,5 +156,10 @@ def test_multiple_payment_priority(self):
         payment_att = self._get_record_from_action(payment_file_action)
 
         # Assert
-        payment_att_content = base64.b64decode(payment_att.datas).decode()
-        self.assertIn(bill.ref, payment_att_content)
+        payment_tree = etree.fromstring(base64.b64decode(payment_att.datas))
+        namespaces = payment_tree.nsmap
+        bills_refs_node = payment_tree.find(
+            ".//PMRQ:RmtInf//PMRQ:Ustrd",
+            namespaces=namespaces,
+        )
+        self.assertIn(bill.ref, bills_refs_node.text)