diff --git a/invoice.py b/invoice.py
index ab31fc4827..a8216a32f0 100644
--- a/invoice.py
+++ b/invoice.py
@@ -1890,7 +1890,7 @@ class InvoiceTax(ModelSQL, ModelView):
         Check if the taxes can be modified
         '''
         for tax in self.browse(cursor, user, ids, context=context):
-            if tax.invoice.state in ('open', 'paid', 'cancel'):
+            if tax.invoice.state in ('open', 'paid'):
                 self.raise_user_error(cursor, 'modify',
                         context=context)
         return