diff --git a/src/open_inwoner/openklant/migrations/0026_contactform_subject_config_default.py b/src/open_inwoner/openklant/migrations/0026_contactform_subject_config_default.py
new file mode 100644
index 0000000000..2128c31c1e
--- /dev/null
+++ b/src/open_inwoner/openklant/migrations/0026_contactform_subject_config_default.py
@@ -0,0 +1,42 @@
+# Generated by Django 4.2.18 on 2025-03-04 13:08
+
+from django.db import migrations
+from django.db.models import Q
+
+
+def set_default_for_klant_config(apps, _):
+    ContactFormSubject = apps.get_model("openklant", "ContactFormSubject")
+    ESuiteKlantConfig = apps.get_model("openklant", "ESuiteKlantConfig")
+    OpenKlant2Config = apps.get_model("openklant", "OpenKlant2Config")
+
+    for contact_form_subject in ContactFormSubject.objects.filter(
+        Q(esuite_config__isnull=True) | Q(openklant_config__isnull=True)
+    ):
+        contact_form_subject.esuite_config = ESuiteKlantConfig.objects.first()
+        contact_form_subject.openklant_config = OpenKlant2Config.objects.first()
+        contact_form_subject.save()
+
+
+def delete_default_for_klant_config(apps, _):
+    ContactFormSubject = apps.get_model("openklant", "ContactFormSubject")
+
+    for contact_form_subject in ContactFormSubject.objects.filter(
+        Q(esuite_config__isnull=False) | Q(openklant_config__isnull=False)
+    ):
+        contact_form_subject.esuite_config = None
+        contact_form_subject.openklant_config = None
+        contact_form_subject.save()
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("openklant", "0025_esuiteklantconfig_send_klantcontact_confirmation_email"),
+    ]
+
+    operations = [
+        migrations.RunPython(
+            code=set_default_for_klant_config,
+            reverse_code=delete_default_for_klant_config,
+        )
+    ]
diff --git a/src/open_inwoner/openklant/tests/test_migrations.py b/src/open_inwoner/openklant/tests/test_migrations.py
new file mode 100644
index 0000000000..ffd29b967d
--- /dev/null
+++ b/src/open_inwoner/openklant/tests/test_migrations.py
@@ -0,0 +1,31 @@
+from open_inwoner.utils.tests.test_migrations import TestSuccessfulMigrations
+
+
+class ContactFormSubjectConfigMigrationTest(TestSuccessfulMigrations):
+    migrate_from = "0025_esuiteklantconfig_send_klantcontact_confirmation_email"
+    migrate_to = "0026_contactform_subject_config_default"
+    app = "openklant"
+
+    def setUpBeforeMigration(self, app):
+        ContactFormSubject = app.get_model("openklant", "ContactFormSubject")
+        ESuiteKlantConfig = app.get_model("openklant", "ESuiteKlantConfig")
+        OpenKlant2Config = app.get_model("openklant", "OpenKlant2Config")
+
+        self.esuite_config_1 = ESuiteKlantConfig.objects.create()
+        self.esuite_config_2 = ESuiteKlantConfig.objects.create()
+        self.openklant_config_1 = OpenKlant2Config.objects.create()
+        self.openklant_config_2 = OpenKlant2Config.objects.create()
+
+        for contact_form_subject in ContactFormSubject.objects.all():
+            contact_form_subject.esuite_config = None
+            contact_form_subject.openklant_config = None
+            contact_form_subject.save()
+
+    def test_set_default_config(self):
+        ContactFormSubject = self.apps.get_model("openklant", "ContactFormSubject")
+
+        for contact_form_subject in ContactFormSubject.objects.all():
+            self.assertEqual(contact_form_subject.esuite_config, self.esuite_config_1)
+            self.assertEqual(
+                contact_form_subject.openklant_config, self.openklant_config_1
+            )