diff --git a/addons/sale/models/sale.py b/addons/sale/models/sale.py
index f226767ba6f..eabb9a28912 100644
--- a/addons/sale/models/sale.py
+++ b/addons/sale/models/sale.py
@@ -372,10 +372,11 @@ class SaleOrder(models.Model):
             raise UserError(_('There is no invoicable line.'))
 
         for invoice in invoices.values():
+            invoice.compute_taxes()
             if not invoice.invoice_line_ids:
                 raise UserError(_('There is no invoicable line.'))
             # If invoice is negative, do a refund invoice instead
-            if invoice.amount_untaxed < 0:
+            if invoice.amount_total < 0:
                 invoice.type = 'out_refund'
                 for line in invoice.invoice_line_ids:
                     line.quantity = -line.quantity