Reverse sales tax.

How to use the reverse sales tax

Enter tax-inclusive price, and sales tax (%). Choose the currency for your inputs and read the result as you change the values.

How it works and formula

Before-tax price = inclusive price ÷ (1 + tax rate). Tax = inclusive price − before-tax price.

Worked example

Result
Before tax $100.00 · Tax $8.00

Try a second calculation

Start with the USD worked example above and change only sales tax (%) to 10. Select Calculate. Your result should read:

Before tax $98.18 · Tax $9.82

Then enter 5 in the same field. Compare the result with the first scenario row. Holding every other input steady lets you see exactly how this one change affects the calculation.

Choosing your inputs

Copy a tax-inclusive amount covering purchases at one rate. Enter the rate that was applied to that amount. If the receipt mixes exempt items and items taxed at different rates, isolate each group and calculate it separately before adding the results.

How to interpret the result

The recovered pre-tax price plus the recovered tax should reproduce the inclusive amount within display rounding. Subtracting the stated percentage directly from the final amount uses the wrong base and generally overstates the tax.

Frequently asked questions