How tax is computed before discount and reduced proportionally
Learn how the engine prices and taxes every element before applying discounts and then claws back the tax on the discounted amount.
The engine prices and taxes every element first, THEN applies discounts, and finally claws back the tax on the discounted amount. When prices include tax, the discount stays pre-tax and the absolute discount is shown at the amount entered, rather than adding the clawed-back tax into the discount value.
At quotation level the same rule applies: net tax = product tax × (1 − total discount / product cost), plus the equivalent for service charges.
✓ Verificato nel prodotto il 16 ottobre 2026Client-visible consequences: (1) the Tax column/row goes DOWN when a discount is added — correct, tax is charged on the post-discount amount. (2) When prices are set to include tax, the discount is shown at its pre-tax value; it is no longer increased by the tax portion, so the discount amount you see matches the amount you entered.
Elements with different tax rates each get a discount share proportional to price, so the effective tax relief blends the rates: the quotation's Tax line is the product tax x (1 - total discount / product price), taken over all products. The per-row Discount and Tax columns differ: an item-type discount (e.g. Woodwork) is shared only among the rows of that type, each taxed at its own rate, so the rows' Tax can add up to a different figure than the Tax line.
✓ Verificato nel prodotto il 19 ottobre 2026