Apply Discount, Then Tax (Order Matters)

Excel Formulas › Business

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Discount first, then tax — that’s the usual (and customer-friendly) order, because tax is charged on what you actually pay. Get the sequence right and the final total is correct to the cent.


Quick formula: for price B1, discount B2, tax B3:
=B1 * (1 - B2) * (1 + B3)
Apply the discount to the price, then tax the discounted amount. One clean expression.

Functions used (tap for the full reference guide):

The example

$100 list, 20% off, then 8% tax.

AB
1StepAmount
2List$100.00
3After 20% off$80.00
4+ 8% tax$86.40

The formula

Discount, then tax the result:

=B1 * (1 - B2) * (1 + B3) // 100 × 0.80 × 1.08 = 86.40

How it works

Two factors applied in the right order:

  1. (1 − discount) takes the price down — 20% off is × 0.80.
  2. (1 + tax) then grosses up the discounted amount — tax on what the customer pays.
  3. Chaining them gives the final total in one cell. Show the intermediate discounted price if the receipt needs it.
  4. Order matters for the tax base: taxing first then discounting changes the tax (and is usually wrong for retail).

When order doesn’t change the total: multiplying by 0.80 and 1.08 commutes mathematically — the total is the same either way. What changes is the tax amount and what’s legally the taxable base. For correct tax reporting, tax the post-discount price.

Try it: interactive demo

Live demo

Set price, discount, tax.

Discounted · Total

Variations

Show the tax amount

On the discounted price:

=B1*(1-B2)*B3

Stacked discounts

Two discounts then tax:

=B1*(1-d1)*(1-d2)*(1+tax)

Tax-exempt items

Skip the tax factor:

=B1*(1-B2)

Pitfalls & errors

Tax the post-discount price. For retail, tax is charged on what the customer actually pays — discount first.

Stacked discounts multiply. 20% then 10% off is ×0.80×0.90 = 28% off, not 30%.

Round once at the end. Rounding the discounted price and again after tax can drift a penny; round the final total.

Practice workbook

📊
Download the free Apply Discount, Then Tax (Order Matters) practice workbook
A discount-then-tax sheet with the tax-amount, stacked-discount, and exempt variants, plus 4 challenges with answers. No sign-up required.

Frequently asked questions

How do I apply a discount then tax in Excel?
Use =price * (1 - discount) * (1 + tax). The discount lowers the price and tax is applied to the discounted amount.
Does it matter whether I discount or tax first?
The final total is the same mathematically, but the taxable base differs. For correct tax reporting, tax the post-discount price.
How do I stack two discounts?
Multiply the factors: =price*(1-d1)*(1-d2)*(1+tax). Two discounts multiply rather than add.

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Related formulas: Invoice total with tax · Quantity discount pricing · Markup chain

Function references: ROUND