Free Tax Calculator
Reverse Sales Tax Calculator
Find the original pre-tax price and sales tax amount when you already know the final tax-inclusive total.
Enter your numbers
Enter the total price including sales tax and the applicable tax rate to calculate the original price before tax.
Enter the final amount paid after sales tax.
Enter the sales tax rate applied to the purchase.
Results
Enter the total price and sales tax rate to see the results.
Example
If the total price is $108 and the sales tax rate is 8%, the price before tax is $100 and the sales tax is $8.
What is reverse sales tax?
Reverse sales tax means working backward from a final price that already includes tax to estimate the original pre-tax price and the tax amount.
This can be useful when a receipt, invoice, or total amount includes sales tax but does not clearly show the original price before tax.
How to calculate reverse sales tax
Divide the tax-inclusive total by one plus the sales tax rate expressed as a decimal. Then subtract the pre-tax price from the total to calculate the tax amount.
Pre-Tax Price = Total Price ÷ (1 + Sales Tax Rate)
Sales Tax = Total Price − Pre-Tax Price
Reverse sales tax example
Suppose the final price is $108 and the sales tax rate is 8%.
Total Price: $108
Sales Tax Rate: 8%
Pre-Tax Price: $100
Sales Tax: $8
When is a reverse sales tax calculator useful?
Receipts and Invoices
Estimate the original price when only a tax-inclusive total is shown.
Business Bookkeeping
Separate sales tax from a total amount for simplified internal analysis.
Purchase Analysis
Compare the original item price with the tax added to the transaction.
Price Verification
Check whether a tax-inclusive total is consistent with the stated tax rate.
Sales tax calculator vs. reverse sales tax calculator
A regular sales tax calculator begins with a price before tax and calculates the final total after tax.
A reverse sales tax calculator begins with the final total and works backward to estimate the pre-tax price and tax amount.
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Markup Calculator →Frequently Asked Questions
How do I remove sales tax from a total?
Divide the tax-inclusive total by one plus the tax rate written as a decimal. The result is the estimated pre-tax price.
What is the pre-tax price of $108 with 8% tax?
The pre-tax price is $100 and the sales tax amount is $8.
Why can't I just subtract 8% from the final price?
Because the tax percentage is calculated from the original pre-tax price, not from the larger tax-inclusive total.
Does this calculator find the correct local sales tax rate?
No. Enter the tax rate that applies to the specific transaction you want to calculate.
Can I use this calculator for tax-inclusive receipts?
Yes. If you know the total amount and applicable tax rate, the calculator can estimate the original price and tax portion.
This reverse sales tax calculator provides simplified estimates for general informational and educational purposes. Actual tax treatment, taxable items, exemptions, sourcing rules, and rates vary by jurisdiction.