Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Add sales tax onto a price, or reverse a tax-inclusive total back to the pre-tax price.
Sometimes you know a pre-tax price and need the tax-inclusive total; other times you have a receipt's final total and need to back out how much was pre-tax versus tax (a common accounting or expense-reporting need). This single calculator handles both directions with the same underlying formula, also covering the identical "Reverse Sales Tax Calculator" search intent.
Choose "Add Tax" if you have a pre-tax price and want the total, or "Reverse" if you have a tax-inclusive total and want the pre-tax price. Enter your amount and local sales tax rate.
Add Tax: Total = Pre-Tax Amount × (1 + Tax Rate)
Reverse: Pre-Tax Amount = Total ÷ (1 + Tax Rate)
Use reverse mode for expense reports or accounting when you need to separate the tax component from a receipt's total for reimbursement or bookkeeping purposes.
Say a hypothetical receipt shows a total of $250.00 and the combined local rate is 7.5%. Dividing by 1.075 gives a pre-tax amount of $232.56, so the tax was $17.44. If you had subtracted 7.5% from $250 instead, you would have arrived at $231.25, which is off by about $1.31 and would produce a wrong tax figure in your books. On a single receipt that may seem small, but across a month of expenses the errors add up, which is why the divide-by-(1 + rate) approach is the right one.
The number you enter should be the total rate charged at the point of sale, usually the sum of a state rate, a county or city rate, and possibly a special district rate. A store address can be in a different rate area than the mailing address of the same town. If you are unsure, your state revenue department often has a lookup tool, or you can check a printed receipt where the tax amount and subtotal are both shown and compute the rate as tax divided by subtotal.
Besides expense reports, this tool helps when comparing a tax-inclusive price at a store with a tax-exclusive online listing, planning the true cost of a large purchase like an appliance, or working out how much sales tax a small business collected from daily totals. For business filings, rely on your point-of-sale records and consult your state's guidance or an accountant, since exemptions and filing obligations vary by jurisdiction.
Because the tax rate was originally applied to the smaller pre-tax amount, not the larger total -- dividing the total by (1 + rate) correctly reverses that calculation, while a straight percentage subtraction slightly overstates the tax removed.
Yes significantly -- combined state, county, city, and special district sales tax rates can vary widely even within the same state, so always use your specific local combined rate.
Divide the tax amount by the pre-tax subtotal and multiply by 100. The result is the rate that was applied, which you can then use here.
Only if those amounts are taxed in your area. In many places tips are not taxed, so exclude them from the amount you enter.
Rounding rules differ by merchant. The calculator rounds the final displayed values, and a register may round each item instead.
Reference: Internal Revenue Service