Calculate sales tax from a pre-tax amount or work backward from a tax-inclusive total.
To calculate sales tax, multiply the amount before tax by the applicable sales tax rate.
$1,000 × 8% = $80 sales tax
$1,000 + $80 = $1,080 total
If the total already includes sales tax, divide the total by 1 plus the tax rate. Do not subtract the tax percentage from the inclusive total.
$1,080 ÷ 1.08 = $1,000 before tax
$1,080 − $1,000 = $80 sales tax
Adding sales tax
Sales tax = Amount before tax × Tax rate
Total = Amount before tax + Sales tax
Removing sales tax
Amount before tax = Tax-inclusive total ÷ (1 + Tax rate)
Sales tax = Tax-inclusive total − Amount before tax
Before tax means sales tax has not yet been added. After tax means sales tax is included in the displayed total.
$100 before 8% sales tax becomes $108 after tax.
A $100 price with 8% sales tax becomes $108. Subtracting 8% of $108 gives $99.36, which is not the original $100 price.
Instead: $108 ÷ 1.08 = $100.
An invoice with sales tax can show the subtotal before tax, the sales tax rate, the sales tax amount, and the total including tax. In the Invoice Generator, tax is a document-level percentage you enter after discounts. The generator does not decide whether an item is taxable or which rate applies.
Check a full invoice total in the Invoice Calculator, or see Creating Invoices for a walkthrough.
Sales tax and VAT are different tax systems, even though both can change the total amount charged. Use this calculator for a user-entered sales tax rate, and the VAT Calculator when you need to add or remove VAT.