diff --git a/src/openklant/components/klantinteracties/api/tests/test_partijen.py b/src/openklant/components/klantinteracties/api/tests/test_partijen.py
index 2d486409..9e8cbf7d 100644
--- a/src/openklant/components/klantinteracties/api/tests/test_partijen.py
+++ b/src/openklant/components/klantinteracties/api/tests/test_partijen.py
@@ -2022,6 +2022,139 @@ def test_destroy_partij_identificator(self):
         data = response.json()
         self.assertEqual(data["count"], 0)
 
+    def test_invalid_choice_partij_identificator_code_register(self):
+        url = reverse("klantinteracties:partijidentificator-list")
+        partij = PartijFactory.create()
+        data = {
+            "identificeerdePartij": {"uuid": str(partij.uuid)},
+            "anderePartijIdentificator": "anderePartijIdentificator",
+            "partijIdentificator": {
+                "codeObjecttype": "natuurlijk_persoon",
+                "codeSoortObjectId": "bsn",
+                "objectId": "123456789",
+                "codeRegister": "test",
+            },
+        }
+        response = self.client.post(url, data)
+        self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
+        self.assertEqual(response.data["code"], "invalid")
+        self.assertEqual(response.data["title"], "Invalid input.")
+        self.assertEqual(
+            response.data["invalid_params"][0]["name"],
+            "partijIdentificator.codeRegister",
+        )
+        self.assertEqual(response.data["invalid_params"][0]["code"], "invalid_choice")
+        self.assertEqual(
+            response.data["invalid_params"][0]["reason"],
+            '"test" is een ongeldige keuze.',
+        )
+
+    def test_invalid_choice_partij_identificator_code_objecttype(self):
+        url = reverse("klantinteracties:partijidentificator-list")
+        partij = PartijFactory.create()
+        data = {
+            "identificeerdePartij": {"uuid": str(partij.uuid)},
+            "anderePartijIdentificator": "anderePartijIdentificator",
+            "partijIdentificator": {
+                "codeObjecttype": "test",
+                "codeSoortObjectId": "bsn",
+                "objectId": "123456789",
+                "codeRegister": "brp",
+            },
+        }
+        response = self.client.post(url, data)
+        self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
+        self.assertEqual(response.data["code"], "invalid")
+        self.assertEqual(response.data["title"], "Invalid input.")
+        self.assertEqual(
+            response.data["invalid_params"][0]["name"],
+            "partijIdentificator.codeObjecttype",
+        )
+        self.assertEqual(response.data["invalid_params"][0]["code"], "invalid_choice")
+        self.assertEqual(
+            response.data["invalid_params"][0]["reason"],
+            '"test" is een ongeldige keuze.',
+        )
+
+    def test_invalid_choice_partij_identificator_code_soort_object_id(self):
+        url = reverse("klantinteracties:partijidentificator-list")
+        partij = PartijFactory.create()
+        data = {
+            "identificeerdePartij": {"uuid": str(partij.uuid)},
+            "anderePartijIdentificator": "anderePartijIdentificator",
+            "partijIdentificator": {
+                "codeObjecttype": "natuurlijk_persoon",
+                "codeSoortObjectId": "test",
+                "objectId": "123456789",
+                "codeRegister": "brp",
+            },
+        }
+        response = self.client.post(url, data)
+        self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
+        self.assertEqual(response.data["code"], "invalid")
+        self.assertEqual(response.data["title"], "Invalid input.")
+        self.assertEqual(
+            response.data["invalid_params"][0]["name"],
+            "partijIdentificator.codeSoortObjectId",
+        )
+        self.assertEqual(response.data["invalid_params"][0]["code"], "invalid_choice")
+        self.assertEqual(
+            response.data["invalid_params"][0]["reason"],
+            '"test" is een ongeldige keuze.',
+        )
+
+    def test_invalid_validation_partij_identificator_code_objecttype(self):
+        url = reverse("klantinteracties:partijidentificator-list")
+        partij = PartijFactory.create()
+        data = {
+            "identificeerdePartij": {"uuid": str(partij.uuid)},
+            "anderePartijIdentificator": "anderePartijIdentificator",
+            "partijIdentificator": {
+                "codeObjecttype": "niet_natuurlijk_persoon",
+                "codeSoortObjectId": "bsn",
+                "objectId": "123456789",
+                "codeRegister": "brp",
+            },
+        }
+
+        # ValidationError, "ObjectType keuzes zijn beperkt op basis van CodeRegister."
+        with self.assertRaises(ValidationError):
+            self.client.post(url, data)
+
+    def test_invalid_validation_partij_identificator_code_soort_object_id(self):
+        url = reverse("klantinteracties:partijidentificator-list")
+        partij = PartijFactory.create()
+        data = {
+            "identificeerdePartij": {"uuid": str(partij.uuid)},
+            "anderePartijIdentificator": "anderePartijIdentificator",
+            "partijIdentificator": {
+                "codeObjecttype": "natuurlijk_persoon",
+                "codeSoortObjectId": "kvk_nummer",
+                "objectId": "123456789",
+                "codeRegister": "brp",
+            },
+        }
+        # "CodeSoortObjectId keuzes zijn beperkt op basis van CodeObjectType.",
+        with self.assertRaises(ValidationError):
+            self.client.post(url, data)
+
+    def test_invalid_validation_partij_identificator_object_id(self):
+        url = reverse("klantinteracties:partijidentificator-list")
+        partij = PartijFactory.create()
+        data = {
+            "identificeerdePartij": {"uuid": str(partij.uuid)},
+            "anderePartijIdentificator": "anderePartijIdentificator",
+            "partijIdentificator": {
+                "codeObjecttype": "natuurlijk_persoon",
+                "codeSoortObjectId": "bsn",
+                "objectId": "12",
+                "codeRegister": "brp",
+            },
+        }
+        # "De lengte van de ObjectId moet tussen 8 en 9 liggen."
+        with self.assertRaises(ValidationError):
+            self.client.post(url, data)
+
     def test_valid_validation_partij_identificator(self):
         # All validations pass
         url = reverse("klantinteracties:partijidentificator-list")