How to Calculate Sales Tax Backwards From a Total
The reverse sales tax formula, a calculator, why subtracting the rate is wrong, worked examples at common rates and the spreadsheet formula.
Quick answer: To calculate sales tax backwards, divide the total by 1 plus the tax rate as a decimal. The result is the pre-tax price, and the tax is the difference. With a total of $108.25 at 8.25% sales tax: $108.25 ÷ 1.0825 = $100.00 before tax, so the tax is $8.25. Do not multiply the total by (1 − rate); that gives the wrong answer.
The reverse sales tax formula
pre-tax price = total ÷ (1 + tax rate)Sales tax = total − pre-tax price. Write 8.25% as 0.0825.Work it out
Price before tax
$100.00
Why subtracting the rate gives the wrong answer
Tax is charged on the pre-tax price, not on the total. Taking 8.25% off the total removes 8.25% of a bigger number, so it removes too much.
| Method | Calculation | Result |
|---|---|---|
| Correct: divide | $108.25 ÷ 1.0825 | $100.00 |
| Wrong: subtract the rate | $108.25 × (1 − 0.0825) | $99.32 |
The 68-cent gap grows with the amount. On a $32,475 car purchase at 8.25%, the wrong method understates the pre-tax price by about $204.
Worked examples at common rates
| Total paid | Tax rate | Pre-tax price | Sales tax |
|---|---|---|---|
| $53.50 | 7% | $50.00 | $3.50 |
| $106.25 | 6.25% | $100.00 | $6.25 |
| $1,088.75 | 8.875% | $1,000.00 | $88.75 |
| $27.50 | 10% | $25.00 | $2.50 |
| $432.60 | 6% | $408.11 | $24.49 |
Combined state and local rates
In most states the rate at the register is the state rate plus county, city and special district rates. Use the combined rate printed on the receipt. For example, a 6.25% state rate plus 2% local tax gives 8.25% combined, and you divide by 1.0825.
Rounding differences on receipts
Retailers round tax to the cent, often per line item. When you reverse a total that was rounded, the pre-tax price can be off by a cent. That is normal. If you need an exact match, reverse each line item separately.
When you need reverse sales tax
- Expense reports that ask for the net amount and the tax separately.
- Bookkeeping when a receipt shows only the total.
- Checking a quote where the seller gives a tax-inclusive price.
- VAT and GST in other countries, where prices usually include tax: the same formula applies, so a £120 price with 20% VAT is £100 net.
Excel and Google Sheets formula
// Total in A2, tax rate as a percentage in B2 (e.g. 8.25%)
=A2/(1+B2)
// Tax amount
=A2-A2/(1+B2)
// Rounded to the cent
=ROUND(A2/(1+B2),2)Backing out tax at 2026 state rates
The table below backs the tax out of a $100.00 receipt at each state’s base rate and at its average combined state and local rate. Divide your own total by the divisor in the third column to get the pre-tax price.
| State | State rate | Divisor | Pre-tax at state rate | Avg combined rate | Pre-tax at combined rate |
|---|---|---|---|---|---|
| California | 7.25% | 1.0725 | $93.24 | 9.03% | $91.72 |
| Texas | 6.25% | 1.0625 | $94.12 | 8.20% | $92.42 |
| New York | 4.00% | 1.0400 | $96.15 | 8.54% | $92.13 |
| Florida | 6.00% | 1.0600 | $94.34 | 6.98% | $93.48 |
| Illinois | 6.25% | 1.0625 | $94.12 | 8.98% | $91.76 |
| Washington | 6.50% | 1.0650 | $93.90 | 9.57% | $91.27 |
| Tennessee | 7.00% | 1.0700 | $93.46 | 9.61% | $91.23 |
| Colorado | 2.90% | 1.0290 | $97.18 | 7.89% | $92.69 |
Rates: Tax Foundation, State and Local Sales Tax Rates, midyear 2026. Combined rates are population-weighted averages, so the rate on your receipt can be higher or lower. Always use the exact combined rate printed on the receipt when you have it.
Reverse VAT and GST outside the US
The same division works for any tax that is added as a percentage of the net price. Only the rate changes.
| Country and tax | Standard rate | Net price | Tax inside the total |
|---|---|---|---|
| UK VAT | 20% | total ÷ 1.20 | total ÷ 6 |
| Australia GST | 10% | total ÷ 1.10 | total ÷ 11 |
| Canada GST (non-HST provinces) | 5% | total ÷ 1.05 | total ÷ 21 |
| Ontario HST | 13% | total ÷ 1.13 | total × 13 ÷ 113 |
| Germany VAT (standard) | 19% | total ÷ 1.19 | total × 19 ÷ 119 |
The shortcut in the last column is the tax fraction: rate ÷ (100 + rate). That is why Australian bookkeepers say “divide by 11” for GST and UK accountants say “divide by 6” for VAT at 20%. Reduced rates, such as UK 5% VAT on domestic energy, use the same formula with the lower rate.
How to check your answer in 10 seconds
- Multiply back. Pre-tax price × (1 + rate) should return the original total. $93.24 × 1.0725 = $100.00.
- Add the parts. Pre-tax price + tax must equal the total to the cent.
- Sense-check the size. The tax should be a little less than rate × total. At 7.25% on $100 the tax is $6.76, not $7.25.
- Allow one cent. Receipts round each line, so a one-cent gap on a multi-item receipt is normal.
Using reverse sales tax in bookkeeping and expense reports
Accounting software records a purchase as two numbers: the net cost and the tax. When a receipt only shows a tax-inclusive total, split it with the formula before you enter it, so the expense and the tax land in the right accounts.
- Expense claims: many policies reimburse the full total but report the tax separately. Back it out with the receipt’s combined rate.
- VAT and GST registered businesses: input tax you can reclaim is the tax portion only, so the net price goes to the expense account and the tax goes to the VAT or GST control account.
- Tax-inclusive pricing: if you want a shelf price of exactly $20.00 including 8.25% tax, set the pre-tax price to $20.00 ÷ 1.0825 = $18.48.
This guide explains the arithmetic. For filing and reclaim rules, check with your state Department of Revenue, HMRC, the CRA or the ATO, or a qualified accountant.
Checklist: five mistakes to avoid
- Subtracting the rate from the total instead of dividing by 1 + rate
- Using the state rate when the receipt includes county and city tax
- Applying the rate to items that were tax-exempt, such as most groceries in many states
- Rounding the divisor before dividing (use the full 1.0725, not 1.07)
- Backing tax out of shipping or fees that were not taxed
Frequently asked questions
How do I remove sales tax from a total?
Divide the total by 1 plus the tax rate. $107 at 7% tax is $107 ÷ 1.07 = $100 before tax.
How do I calculate sales tax backwards from a total?
Pre-tax price = total ÷ (1 + rate). Sales tax = total − pre-tax price.
Why can I not just subtract the percentage?
Because tax was charged on the lower pre-tax price. Subtracting the rate from the total removes too much.
How do I find the tax rate if I know the price and total?
Divide the total by the pre-tax price, subtract 1 and multiply by 100. $108.25 ÷ $100 − 1 = 8.25%.
Does this work for VAT?
Yes. Divide a VAT-inclusive price by 1 plus the VAT rate. £120 at 20% VAT is £100 net.
Why is my answer a cent off?
Stores round tax to the cent, sometimes per item, so reversing a rounded total can differ by a cent.
Sources and how we checked this guide
- Tax Foundation, State and Local Sales Tax Rates, Midyear 2026
- GOV.UK, VAT rates
- Canada Revenue Agency, Charge and collect the GST/HST: which rate to charge
Every worked number on this page was recalculated with the Reverse Sales Tax Calculator. Rates are reviewed when the Tax Foundation publishes its January and midyear updates.
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