Sales tax calculations depend on the rate and whether your starting amount is before or after tax. Choose the correct direction before calculating.
Add sales tax
To add tax, multiply the pre-tax amount by the rate and add the tax to the original amount. A $100 purchase at 8% tax produces $8 of tax and a $108 total.
Remove sales tax
When a receipt total already includes tax, divide the total by one plus the tax rate. Subtract the pre-tax amount from the total to find the tax portion.
Location and exemptions
Use the combined rate that applies to the purchase location. Local rules, exemptions, shipping and rounding can change the final amount.
- Confirm the rate for the correct address.
- Check whether the item is taxable.
- Round currency at the end of the calculation.
Frequently asked questions
Can I remove tax from a receipt total?
Yes. Choose the remove-tax mode and enter the tax-inclusive total with the applicable rate.
Does the calculator know local exemptions?
No. It applies the rate and mode you enter. Confirm exemptions with the local tax authority or seller.