diff --git a/cotisations/models.py b/cotisations/models.py
index 9865e905..1a593dad 100644
--- a/cotisations/models.py
+++ b/cotisations/models.py
@@ -511,7 +511,7 @@ class Vente(RevMixin, AclMixin, models.Model):
             )
         return
 
-    def create_cotis(self):
+    def create_cotis(self, date_start=False):
         """
         Creates a cotisation without initializing the dates (start and end ar set to self.facture.facture.date) and without saving it. You should use Facture.reorder_purchases to set the right dates.
         """
@@ -522,8 +522,17 @@ class Vente(RevMixin, AclMixin, models.Model):
         if not hasattr(self, "cotisation") and self.type_cotisation:
             cotisation = Cotisation(vente=self)
             cotisation.type_cotisation = self.type_cotisation
-            cotisation.date_start = invoice.date
-            cotisation.date_end = invoice.date
+            if date_start:
+                cotisation.date_start = date_start
+                cotisation.date_end = cotisation.date_start + relativedelta(
+                    months=(self.duration or 0) * self.number,
+                    days=(self.duration_days or 0) * self.number,
+                )
+                self.save()
+                cotisation.save()
+            else:
+                cotisation.date_start = invoice.date
+                cotisation.date_end = invoice.date
 
     def save(self, *args, **kwargs):
         """
diff --git a/cotisations/test_models.py b/cotisations/test_models.py
index bc86b7a7..6e90d882 100644
--- a/cotisations/test_models.py
+++ b/cotisations/test_models.py
@@ -79,6 +79,24 @@ class VenteModelTests(TestCase):
         self.assertEqual(end.month, expected_end.month)
         self.assertEqual(end.year, expected_end.year)
 
+    def test_date_start_cotisation(self):
+        """
+        It should be possible to add a cotisation with a specific start date
+        """
+        v = Vente(
+            facture=self.f,
+            number=1,
+            name="Test purchase",
+            duration=0,
+            duration_days=1,
+            type_cotisation = 'All',
+            prix=0
+        )
+        v.create_cotis(date_start=timezone.make_aware(datetime.datetime(1998, 10, 16)))
+        v.save()
+        self.assertEqual(v.cotisation.date_end, timezone.make_aware(datetime.datetime(1998, 10, 17)))
+
+
     def tearDown(self):
         self.f.delete()
         self.user.delete()