diff --git a/addons/account/models/account.py b/addons/account/models/account.py
index 5d61b7b155f0627129f7949d681d27b65f954966..5151ec75b442a0e8c16b33464d5e95fab12f2d13 100644
--- a/addons/account/models/account.py
+++ b/addons/account/models/account.py
@@ -869,7 +869,7 @@ class AccountTax(models.Model):
                 incl_fixed_amount = incl_percent_amount = 0
             if tax.price_include:
                 if tax.amount_type == 'fixed':
-                    incl_fixed_amount += tax.amount
+                    incl_fixed_amount += quantity * tax.amount
                 elif tax.amount_type == 'percent':
                     incl_percent_amount += tax.amount
         # Start the computation of accumulated amounts at the total_excluded value.
diff --git a/addons/account/tests/test_tax.py b/addons/account/tests/test_tax.py
index cfd5470981bae782e966fb295fcad484ac94722f..806c0e5cda4b454b12aac89247a9a11e8d78cc0e 100644
--- a/addons/account/tests/test_tax.py
+++ b/addons/account/tests/test_tax.py
@@ -232,6 +232,22 @@ class TestTax(AccountTestUsers):
             res
         )
 
+        self.fixed_tax.price_include = True
+        self.fixed_tax.include_base_amount = False
+        res = self.fixed_tax.compute_all(100.0, quantity=2.0)
+        self._check_compute_all_results(
+            180,     # 'base'
+            200,     # 'total_included'
+            180,     # 'total_excluded'
+            [
+                # base , amount     | seq | amount | incl | incl_base
+                # ---------------------------------------------------
+                (180.0, 20.0),    # |  1  |    20  |      |     t
+                # ---------------------------------------------------
+            ],
+            res
+        )
+
     def test_tax_include_base_amount_2(self):
         self.percent_tax.price_include = True
         self.percent_tax.amount = 21.0
diff --git a/addons/point_of_sale/static/src/js/models.js b/addons/point_of_sale/static/src/js/models.js
index d6f3f39b173cee369ff4fa19cf271333313e13f2..b268e88571ce865e3cbfa7d259538d09b9bbaecf 100644
--- a/addons/point_of_sale/static/src/js/models.js
+++ b/addons/point_of_sale/static/src/js/models.js
@@ -1502,7 +1502,7 @@ exports.Orderline = Backbone.Model.extend({
             }
             if(tax.price_include){
                 if(tax.amount_type === 'fixed')
-                    incl_fixed_amount += tax.amount;
+                    incl_fixed_amount += quantity * tax.amount;
                 else if(tax.amount_type === 'percent')
                     incl_percent_amount += tax.amount;
             }
@@ -1518,7 +1518,7 @@ exports.Orderline = Backbone.Model.extend({
             var amount = self._compute_all(tax, base, quantity, false);
 
             if(!tax.price_include || base_gaps.length == 0)
-                return tax_amount;
+                return amount;
 
             var new_gap = base_gaps[base_gaps.length - 1] - amount;