diff --git a/addons/sale/models/sale.py b/addons/sale/models/sale.py
index 781b986bf34..089eed7e253 100644
--- a/addons/sale/models/sale.py
+++ b/addons/sale/models/sale.py
@@ -508,7 +508,7 @@ class SaleOrder(models.Model):
             for tax in line.tax_id:
                 group = tax.tax_group_id
                 res.setdefault(group, 0.0)
-                res[group] += tax.compute_all(line.price_unit, quantity=line.product_uom_qty)['taxes'][0]['amount']
+                res[group] += tax.compute_all(line.price_reduce, quantity=line.product_uom_qty)['taxes'][0]['amount']
         res = sorted(res.items(), key=lambda l: l[0].sequence)
         res = map(lambda l: (l[0].name, formatLang(self.env, l[1], currency_obj=currency)), res)
         return res