diff --git a/addons/account/models/account_move.py b/addons/account/models/account_move.py
index 1ebafd3ce3c..bf0d8196f6d 100644
--- a/addons/account/models/account_move.py
+++ b/addons/account/models/account_move.py
@@ -3332,11 +3332,17 @@ class AccountMoveLine(models.Model):
             # E.g. mapping a 10% price-included tax to a 20% price-included tax for a price_unit of 110 should preserve
             # 100 as balance but set 120 as price_unit.
             if line.tax_ids and line.move_id.fiscal_position_id:
-                line.price_unit = line._get_price_total_and_subtotal()['price_subtotal']
-                line.tax_ids = line.move_id.fiscal_position_id.map_tax(line.tax_ids._origin, partner=line.move_id.partner_id)
-                accounting_vals = line._get_fields_onchange_subtotal(price_subtotal=line.price_unit, currency=line.move_id.company_currency_id)
+                price_subtotal = line._get_price_total_and_subtotal()['price_subtotal']
+                line.tax_ids = line.move_id.fiscal_position_id.map_tax(
+                    line.tax_ids._origin,
+                    partner=line.move_id.partner_id)
+                accounting_vals = line._get_fields_onchange_subtotal(
+                    price_subtotal=price_subtotal,
+                    currency=line.move_id.company_currency_id)
                 amount_currency = accounting_vals['amount_currency']
-                line.price_unit = line._get_fields_onchange_balance(amount_currency=amount_currency).get('price_unit', line.price_unit)
+                business_vals = line._get_fields_onchange_balance(amount_currency=amount_currency)
+                if 'price_unit' in business_vals:
+                    line.price_unit = business_vals['price_unit']
 
             # Convert the unit price to the invoice's currency.
             company = line.move_id.company_id