diff --git a/cotisations/models.py b/cotisations/models.py
index 66a89abb..be25ea68 100644
--- a/cotisations/models.py
+++ b/cotisations/models.py
@@ -52,6 +52,7 @@ from re2o.field_permissions import FieldPermissionModelMixin
 from re2o.mixins import AclMixin, RevMixin
 
 from cotisations.utils import find_payment_method
+from cotisations.validators import check_no_balance
 
 
 # TODO : change facture to invoice
@@ -605,18 +606,6 @@ class Banque(RevMixin, AclMixin, models.Model):
         return self.name
 
 
-def check_no_balance():
-    """This functions checks that no Paiement with is_balance=True exists
-
-    Raises:
-        ValidationError: if such a Paiement exists.
-    """
-    p = Paiement.objects.filter(is_balance=True)
-    if len(p)>0:
-        raise ValidationError(
-            _("There are already payment method(s) for user balance")
-        )
-
 # TODO : change Paiement to Payment
 class Paiement(RevMixin, AclMixin, models.Model):
     """
diff --git a/cotisations/validators.py b/cotisations/validators.py
new file mode 100644
index 00000000..fa8ea2cf
--- /dev/null
+++ b/cotisations/validators.py
@@ -0,0 +1,21 @@
+from django.forms import ValidationError
+from django.utils.translation import ugettext as _
+
+
+def check_no_balance(is_balance):
+    """This functions checks that no Paiement with is_balance=True exists
+
+    Args:
+        is_balance: True if the model is balance.
+
+    Raises:
+        ValidationError: if such a Paiement exists.
+    """
+    from .models import Paiement
+    if not is_balance:
+        return
+    p = Paiement.objects.filter(is_balance=True)
+    if len(p) > 0:
+        raise ValidationError(
+            _("There are already payment method(s) for user balance")
+        )