How to Back Out Sales Tax From a Tax-Inclusive Total

To back sales tax out of a tax-inclusive total, divide the total by (1 + the tax rate as a decimal). The result is the pre-tax price, and the difference between the total and that price is the tax. For a $107.25 receipt at a 7.25% rate, the math is $107.25 ÷ 1.0725 = $100.00 pre-tax, leaving $7.25 in tax. The fastest way to run any version of this is the sales tax calculator, but the formula is simple enough to do on a phone.

This is the reverse of normal sales tax math. Normally you start with a pre-tax price and add tax. Here you start with the final, tax-included number on a receipt or invoice and work backward to separate the price from the tax. Business owners do this constantly for bookkeeping, expense reports, and tax filings, and shoppers do it to check what they actually paid. The trap is that the obvious shortcut, subtracting the tax rate from the total, gives the wrong answer. This guide shows the correct formula, walks through several worked examples, explains exactly why the shortcut fails, and gives you a clean way to do it in Excel.

The formula for backing out sales tax

The reverse sales tax formula has two short steps:

• Pre-tax price = Total ÷ (1 + rate)
• Tax = Total − Pre-tax price

The rate is written as a decimal, so 7.25% becomes 0.0725 and the divisor becomes 1.0725. A 10% rate becomes 1.10, and an 8.875% combined city rate becomes 1.08875. That single divisor does all the work. Once you have the pre-tax price, the tax is just the leftover.

Why divide instead of subtract? Because the tax on a receipt was calculated on the pre-tax price, not on the total. The total already contains the price plus a percentage of that same price. Dividing by (1 + rate) unwinds that relationship exactly. Subtracting the rate from the total applies the percentage to the wrong, larger base, so it overshoots every time.

Worked example: a single item

Say a receipt shows a final charge of $53.61 and you know the local rate is 8.25%. Back the tax out:

1. Convert the rate: 8.25% = 0.0825, so the divisor is 1.0825.
2. Pre-tax price: $53.61 ÷ 1.0825 = $49.52.
3. Tax: $53.61 − $49.52 = $4.09.

Check it forward: $49.52 × 0.0825 = $4.09, and $49.52 + $4.09 = $53.61. The numbers tie out, which is the proof that you backed the tax out correctly. Any time you finish a reverse calculation, run it forward to confirm the pieces add back to the original total.

Worked example: a whole receipt

The same method works on a full receipt total, as long as every item on it was taxed at the same rate. Suppose a business expense receipt totals $162.38 at a 6.00% rate:

• Pre-tax subtotal: $162.38 ÷ 1.06 = $153.19.
• Sales tax: $162.38 − $153.19 = $9.19.

That $153.19 is the figure you record as the deductible or reimbursable amount, and $9.19 is the tax line. If a receipt mixes taxed and tax-exempt items (groceries and prescriptions are exempt in many states), this whole-receipt shortcut breaks down, because the tax was only charged on part of the total. In that case, back the tax out of the taxed items only.

The common mistake: subtracting the rate

The wrong way to back out tax is to multiply the total by (1 − rate), as if you could just lop the percentage off. On that same $107.25 total at 7.25%, the shortcut gives:

$107.25 × (1 − 0.0725) = $107.25 × 0.9275 = $99.47

That is wrong. The true pre-tax price is $100.00, so the shortcut undershoots by $0.53 on a single small purchase. The error grows with the price and the rate. On a $1,284.59 tax-inclusive total at a combined 8.875% rate, the correct method gives a pre-tax price of $1,179.88 and tax of $104.71, while the subtract-the-rate shortcut would be off by enough to throw your books out of balance. Always divide; never subtract the rate.

Reverse sales tax at a glance

This table backs the tax out of a $100.00 tax-inclusive total across common US rate levels, so you can see how much of a fixed final price is actually tax. Notice that the higher the rate, the smaller the pre-tax price hiding inside the same $100.

One subtle point this table makes clear: the tax inside a $100 total is always less than the headline rate times $100. At 10%, the tax is $9.09, not $10.00, because the $10 the seller would have added was charged on the $90.91 base, not on the full $100. Backing it out correctly recovers that distinction.

How to back out sales tax in Excel or Google Sheets

For more than a couple of receipts, a spreadsheet beats mental math. Put the tax-inclusive total in cell A2 and the rate (as a decimal) in B2, then:

• Pre-tax price in C2: =A2/(1+B2)
• Tax amount in D2: =A2-C2

If you would rather type the rate as a whole number like 7.25 in B2, divide it by 100 inside the formula: =A2/(1+B2/100). Wrap each formula in ROUND(...,2) to keep the cents clean, for example =ROUND(A2/(1+B2),2). Copy the row down a column of receipts and the whole batch is separated into price and tax in seconds. The same approach works for backing the tax out of a markup or margin figure, which our markup calculator and profit margin calculator handle if you need the related pricing math.

When you would back out tax

The reverse calculation shows up more than you might expect:

• Bookkeeping and accounting. Many point-of-sale systems and petty-cash receipts give you only the tax-inclusive total. To post the sale correctly, you split it into net revenue and a sales-tax-payable amount.
• Expense reports and reimbursements. Some employers reimburse the pre-tax amount, or need the tax broken out separately for their own filings.
• Tax-inclusive pricing. If you advertise a flat "$20 out the door" price, you have to back out the tax to know your true revenue per sale.
• Checking a charge. Shoppers reverse the math to confirm a register rang up the right rate, especially in cities where state, county, and city taxes stack into an unusual combined number.

For the forward version of this math, adding tax to a price, the same sales tax calculator handles both directions. And because sales tax is a flat percentage of price rather than a multi-stage tax, the reverse method here is identical to backing out a VAT figure overseas, which our VAT calculator covers for international invoices.

A note on rounding

Sales tax is rounded to the nearest cent at the register, so a backed-out figure can occasionally land a penny away from the original line items. That tiny gap comes from rounding, not from a mistake in your method. For a quick sanity check on how percentages and their reverses relate, our percentage calculator lets you confirm the pieces. The authoritative source on how sales and use tax actually work, state by state, is the U.S. government's guide to sales tax, which is worth a look if you are reconciling charges across different jurisdictions.

Bottom line: to back sales tax out of any total, divide by (1 + rate), then subtract to find the tax, and always run it forward to check. When you would rather skip the arithmetic, drop your total and rate into the free sales tax calculator and read the pre-tax price and tax straight off the screen.

Frequently asked questions

How do I back out sales tax from a total?

Divide the tax-inclusive total by (1 + the tax rate written as a decimal) to get the pre-tax price, then subtract that from the total to find the tax. For example, $107.25 at a 7.25% rate is $107.25 ÷ 1.0725 = $100.00 pre-tax, leaving $7.25 in tax. Always run it forward afterward to confirm the price plus tax equals the original total.

What is the formula to remove sales tax from a price?

The formula is pre-tax price = total ÷ (1 + rate), and tax = total − pre-tax price. Write the rate as a decimal, so 8.25% becomes 0.0825 and the divisor is 1.0825. On a $53.61 total at 8.25%, the pre-tax price is $49.52 and the tax is $4.09. This unwinds the original calculation exactly because the tax was charged on the pre-tax base.

Why can't I just subtract the tax rate from the total?

Subtracting the rate gives the wrong answer because the tax was calculated on the smaller pre-tax price, not on the larger total. Multiplying $107.25 by (1 − 0.0725) returns $99.47, but the true pre-tax price is $100.00, an error of $0.53. The gap grows with bigger amounts and higher rates, so you must divide by (1 + rate) instead of subtracting.

How much of a $100 total is sales tax at 10%?

At a 10% rate, a $100 tax-inclusive total contains $90.91 in price and $9.09 in tax, found by dividing $100 by 1.10. The tax is $9.09, not $10.00, because the $10 a seller would add is charged on the $90.91 base, not on the full $100. Backing the tax out correctly recovers that distinction every time.

How do I back out sales tax in Excel?

Put the tax-inclusive total in A2 and the rate as a decimal in B2, then use =A2/(1+B2) for the pre-tax price and =A2-B2... use =A2-C2 for the tax. If you type the rate as a whole number like 7.25, write =A2/(1+B2/100) instead. Wrap each in ROUND(...,2) to keep clean cents, then copy the row down a list of receipts.

Can I back tax out of a receipt with multiple items?

Yes, as long as every item on the receipt was taxed at the same rate; just divide the whole total by (1 + rate). A $162.38 receipt at 6% breaks into $153.19 pre-tax and $9.19 tax. But if the receipt mixes taxed and exempt items, like groceries or prescriptions, the shortcut fails, so back the tax out of only the taxed portion.

Why is my backed-out tax off by a penny?

A one-cent gap usually comes from rounding, not a mistake. Registers round each line's tax to the nearest cent, so reversing the math can land a penny from the original. This is normal and harmless for most bookkeeping. If exact line-level accuracy matters, back the tax out of each taxed item separately rather than from the combined total.

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