diff --git a/passerelle/apps/api_particulier/models.py b/passerelle/apps/api_particulier/models.py
index 70de9b13..e9638ea7 100644
--- a/passerelle/apps/api_particulier/models.py
+++ b/passerelle/apps/api_particulier/models.py
@@ -170,11 +170,13 @@ class APIParticulier(BaseResource):
                   },
               })
     def v2_avis_imposition(self, request, numero_fiscal, reference_avis, user=None):
-        if not numero_fiscal.strip() or not reference_avis.strip():
-            raise APIError('missing numero_fiscal or reference_avis', status_code=400)
+        numero_fiscal = numero_fiscal.strip()[:13]
+        reference_avis = reference_avis.strip()[:13]
+        if len(numero_fiscal) < 13 or len(reference_avis) < 13:
+            raise APIError('bad numero_fiscal or reference_avis, must be 13 chars long', status_code=400)
         return self.get('v2/avis-imposition', params={
             'numeroFiscal': numero_fiscal,
-            'referenceAvis': reference_avis[:13],
+            'referenceAvis': reference_avis,
         }, user=user)
 
     @endpoint(perm='can_access',
diff --git a/tests/test_api_particulier.py b/tests/test_api_particulier.py
index c043f4dc..3744d23b 100644
--- a/tests/test_api_particulier.py
+++ b/tests/test_api_particulier.py
@@ -155,8 +155,8 @@ def resource(db):
 def test_error(app, resource, mock_api_particulier):
     vector = [
         (['impots_svair', 'avis-imposition'], {
-            'numero_fiscal': 12,
-            'reference_avis': 15,
+            'numero_fiscal': '1234567890123',
+            'reference_avis': '3210987654321',
         }),
         (['caf_famille', 'situation-familiale'], {
             'code_postal': 12,
@@ -223,6 +223,35 @@ def test_error(app, resource, mock_api_particulier):
             for endpoint in endpoints:
                 do(endpoint, params)
 
+    resp = endpoint_get(
+        '/api-particulier/test/avis-imposition',
+        app,
+        resource,
+        'avis-imposition',
+        params={
+            'numero_fiscal': '  1234567890',  # too short
+            'reference_avis': '3210987654321',
+            'user': 'John Doe',
+        })
+    assert resp.status_code == 200
+    assert resp.json['err'] == 1
+    assert resp.json['data'] is None
+    assert 'must be 13 chars long' in resp.json['err_desc']
+    resp = endpoint_get(
+        '/api-particulier/test/avis-imposition',
+        app,
+        resource,
+        'avis-imposition',
+        params={
+            'numero_fiscal': '1234567890123',
+            'reference_avis': '32109876543   ',  # too short
+            'user': 'John Doe',
+        })
+    assert resp.status_code == 200
+    assert resp.json['err'] == 1
+    assert resp.json['data'] is None
+    assert 'must be 13 chars long' in resp.json['err_desc']
+
 
 def test_avis_imposition(app, resource, mock_api_particulier):
     resp = endpoint_get(
@@ -231,11 +260,27 @@ def test_avis_imposition(app, resource, mock_api_particulier):
         resource,
         'avis-imposition',
         params={
-            'numero_fiscal': 12,
-            'reference_avis': 15,
+            'numero_fiscal': '1234567890123',
+            'reference_avis': '3210987654321',
             'user': 'John Doe',
         })
+    assert resp.status_code == 200
     assert resp.json['data']['montantImpot'] == 2165
+    assert resp.json['err'] == 0
+
+    resp = endpoint_get(
+        '/api-particulier/test/avis-imposition',
+        app,
+        resource,
+        'avis-imposition',
+        params={
+            'numero_fiscal': '1234567890123X',   # 14 chars : will be cutted
+            'reference_avis': '3210987654321X',  # idem
+            'user': 'John Doe',
+        })
+    assert resp.status_code == 200
+    assert resp.json['data']['montantImpot'] == 2165
+    assert resp.json['err'] == 0
 
 
 def test_situation_familiale(app, resource, mock_api_particulier):
@@ -276,8 +321,8 @@ def test_api_particulier_dont_log_not_found(app, resource, mock, should_log):
             resource,
             'avis-imposition',
             params={
-                'numero_fiscal': 12,
-                'reference_avis': 15,
+                'numero_fiscal': '1234567890123',
+                'reference_avis': '3210987654321',
             })
     logs = ResourceLog.objects.all()
     assert logs.count() == 3