How Discount and Tax Are Applied
Discounts and taxes are applied sequentially, not simultaneously. The discount is applied to the original price first, reducing it. Then the tax is calculated on the discounted price, not the original. This is the standard retail convention in most countries.
- Step 1: Discount Amount = Original Price × (Discount % ÷ 100)
- Step 2: Price After Discount = Original Price − Discount Amount
- Step 3: Tax Amount = Price After Discount × (Tax % ÷ 100)
- Step 4: Final Price = Price After Discount + Tax Amount
For example, a $100 item with a 20% discount and 10% tax: discount = $20, price after discount = $80, tax = $8, final price = $88. You saved $12 compared to paying full price plus tax ($110).
Effective Discount Rate
The effective discount rate is the percentage you actually save compared to the original price, after accounting for the tax applied on the discounted price. In the example above, you pay $88 vs $100 original (ignoring tax) — but compared to the full $110 you would have paid at original price plus tax, you saved $22, which is a 20% effective saving on the pre-tax amount.
If the tax rate is higher than the discount rate, you may end up paying more than the original price — the effective discount rate will show as negative in that case.
Frequently Asked Questions
Is tax calculated on the original price or the discounted price?
In most retail scenarios, tax is applied to the sale price (after discount), not the original price. This calculator follows that convention. Some tax jurisdictions apply tax differently — check local rules if precision is critical for business purposes.
What if I have multiple discounts?
For a single combined discount percentage, you can calculate the equivalent: two sequential discounts of 20% and 10% are not the same as a 30% discount. The combined equivalent is: 1 − (1 − 0.20) × (1 − 0.10) = 1 − 0.72 = 28%. Enter that combined rate into this calculator to see the final price.
What is the difference between a discount and a rebate?
A discount is applied at the point of sale, reducing the price you pay upfront. A rebate is a partial refund applied after purchase — you pay full price, then receive money back. From a financial perspective, a $20 discount and a $20 rebate have the same end cost but different cash flow timing and tax treatment.