Reverse Sales Tax Calculator

Divide the total by 1 plus the tax rate as a decimal. For a $107 total at 7%, divide 107 by 1.07 to get $100. Subtract that from the total to find $7 of tax. Never subtract the percentage from the total directly — sales tax was charged on the original price, not on the tax-inclusive amount, so subtracting always understates the true pre-tax price.

The formula is: pre-tax price equals total divided by (1 + rate ÷ 100). Tax paid is then the total minus that pre-tax price. This is the exact inverse of the forward calculation, where price times (1 + rate) produces the total. Because it inverts by division, the answer is precise rather than an approximation, and it round-trips exactly back to the original figure.

Because percentages are not symmetrical. Adding 7% then subtracting 7% does not return you to the start. The 7% was calculated on the smaller pre-tax price, but subtracting 7% takes it from the larger total, so you remove too much. On a $107 total the error is 49 cents; on a $1,070 total it is $4.90. Division reverses it exactly.

If you know both the pre-tax price and the total, divide the tax amount by the pre-tax price and multiply by 100. A $7 tax on a $100 item is a 7% rate. If your receipt shows only the total, check the retailer's location — combined rates include state, county, city and special district portions, so the rate often differs from your state's headline rate.

Yes. VAT, GST and HST are all calculated as a percentage added to a net price, so the same division reverses them. Enter your VAT or GST rate in place of the sales tax rate — 20% for UK VAT, 5% for Canadian GST, or your local combined rate. The arithmetic is identical; only the name and rate change.

Enter 18 as the rate and the total as the tax-inclusive amount — the same division formula applies, so a ₹1,180 GST-inclusive total divides by 1.18 to give a ₹1,000 base price and ₹180 of GST. 18% is one of India's two standard GST slabs, alongside 5%, since the GST 2.0 rate rationalization took effect on September 22, 2025, replacing the earlier four-slab structure of 5%, 12%, 18% and 28%; a separate 40% rate applies to select luxury and sin goods. There's nothing India-specific about the math itself, only the rate.

Because a state rate alone is usually wrong. US sales tax is levied by state, county, city and special districts at the same time, so two addresses in one state routinely pay different totals. A built-in table showing only state base rates would give most shoppers a confidently incorrect answer. Entering the rate from your receipt is always accurate and never goes out of date.

Expense reports often require the taxable base separated from the tax paid, especially when a receipt shows only one final total. Enter that total and the tax rate printed on the receipt, and the calculator returns the pre-tax price and the tax amount separately. This matters for hotel, restaurant and rental car receipts, where the pre-tax figure is frequently the number a reimbursement policy or a company's expense system actually wants recorded, rather than the tax-inclusive total charged to the card.

Calculating sales tax forward starts from a known price and multiplies it by the tax rate to find what gets added on top. Reversing it starts from the opposite end: you already know the tax-inclusive total and need to find the price that produced it, which requires dividing rather than multiplying. Both directions use the same rate and describe the same transaction, but they solve for different unknowns, which is why they use different arithmetic rather than the same operation run backward.

Retailers filing a sales tax return generally have to report taxable sales separately from the tax collected on them, not the combined total. If a point-of-sale system only exports tax-inclusive totals, the taxable sales figure is found by dividing each total by 1 plus the applicable combined rate, exactly as the Minnesota Department of Revenue's guidance for businesses describes. The result is the number a return actually asks for, with the tax portion accounted for separately from the sales figure.

Yes. Enter the total you paid and the combined sales tax rate for that specific location, then compare the calculator's tax amount to what's itemized on your receipt. If they don't match, the discrepancy usually traces to a wrong rate assumption, a non-taxable item bundled into the total, or a rate that changed since you last checked it, rather than an error in the arithmetic itself. Comparing the two numbers is the fastest way to confirm a receipt before disputing it.

Because sales tax in the United States stacks multiple layers on top of each other: a state rate, plus county, city and sometimes special district rates that apply on top of it. Two addresses in the same state, even a few miles apart, can fall under different combinations of local jurisdictions and end up with different combined rates. That's why a single statewide rate is unreliable for this calculator — the rate printed on the specific receipt is always the accurate one to use.

Occasionally, by a cent or two. Cash registers round the tax amount to the nearest cent on every transaction, while this calculator works with the exact combined rate you enter and doesn't round until the final result. On a small purchase that rounding can shift the answer by a cent; on a larger total it becomes negligible. If the rate is entered correctly, any difference should be a rounding artifact, not a sign the formula itself is wrong.