diff --git a/test.py b/test.py
index 43dd022..c562bdc 100644
--- a/test.py
+++ b/test.py
@@ -71,6 +71,20 @@ class TestValidation(tornado.testing.AsyncHTTPTestCase):
         self.assertIn('valid', validation_result, "Key 'valid' expected in validation result")
         self.assertTrue(validation_result['valid'], "Validation result is expected to be valid==true")
 
+    def test_invalid_entity(self):
+        entity_file = json.load(open('test_cases/invalid/invalid_iban.json','r'))
+
+        response = self.fetch('/v0/validate',
+                              method='POST',
+                              body=json.dumps(entity_file))
+        
+        self.assertEqual(200, response.code, "Validation must always return 200")
+
+        validation_result = json.loads(response.body.decode())
+
+        self.assertIn('valid', validation_result, "Key 'valid' expected in validation result")
+        self.assertFalse(validation_result['valid'], "Validation result is expected to be valid==false")
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/test_cases/invalid/invalid_iban.json b/test_cases/invalid/invalid_iban.json
new file mode 100644
index 0000000..c1357ee
--- /dev/null
+++ b/test_cases/invalid/invalid_iban.json
@@ -0,0 +1,36 @@
+{
+    "finanzdaten": {
+        "bic": "PBNKDEFFXXX",
+        "holder": "",
+        "iban": "DX89370400440532013000",
+        "issuance": "2012-01-01",
+        "reference": "0042",
+        "scan-sepa-mandate": ""
+    },
+    "mitgliederdaten": {
+        "bis": "",
+        "mitgliedsbeitrag": "30",
+        "scan-antrag": "",
+        "schliessberechtigung": "Ja",
+        "spendenbeitrag": "0",
+        "status": "V",
+        "von": "2012-01-01"
+    },
+    "stammdaten": {
+        "address_code": "39104",
+        "address_country": "DE",
+        "address_label": "Max Hackerberg\nLeibnizstr. 32\n39104 Magdeburg",
+        "address_locality": "Magdeburg",
+        "address_region": "",
+        "address_street": "Leibnizstr. 32",
+        "birth_date": "1970-01-01",
+        "birth_location": "Hackstadt",
+        "email": "max.hackerberg@netz39.de",
+        "fullname": "Max Hackerberg",
+        "nickname": "maxH",
+        "pgp-key": "",
+        "ssh-key": ""
+    },
+    "timestamp": "2020-03-25T23:58:11",
+    "id": "6af68"
+}
\ No newline at end of file