How US Sales Tax Works (and Why Your Total Varies by ZIP Code)

Last updated: 2026-06-13

There is no national US sales tax. The rate you pay is the sum of a state rate plus county, city, and special-district rates layered on top — which is why the same item can cost a different total two towns apart. Sales tax is added at the point of sale and collected by the seller, not baked into the shelf price.

State plus local: how the combined rate is built

Most states set a base rate and then let local jurisdictions add their own. A state base of 6% with a 2% county rate and a 1% city rate produces a 9% combined rate at the register. Five states (Alaska, Delaware, Montana, New Hampshire, and Oregon) have no statewide sales tax, though some still allow local taxes.

Destination vs. origin sourcing

Most states are destination-based: the rate is set by where the buyer takes possession (the ship-to address), not where the seller sits. A handful use origin-based sourcing for in-state sales. For online sellers this matters enormously, because it decides which jurisdiction's rate applies to each order.

Nexus: when a seller must collect

A business only has to collect sales tax in states where it has nexus — a sufficient connection. Physical nexus comes from an office, warehouse, or employees. Economic nexus, established after the 2018 Supreme Court Wayfair decision, is triggered by crossing a sales or transaction threshold in a state (commonly $100,000 in sales or 200 transactions) even with no physical presence there.

Tax-inclusive vs. tax-exclusive pricing

US prices are almost always tax-exclusive: the tag shows the pre-tax price and tax is added at checkout. Many other countries quote tax-inclusive prices (the tag is what you pay). If you know a total that already includes tax and need to work backward to the pre-tax amount, that is the reverse calculation.

Try the toolReverse Sales Tax CalculatorBack sales tax out of a total: enter the price you paid and the tax rate to find the pre-tax price and exact tax amount. Uses price ÷ (1 + rate).

What is usually exempt

Groceries and prescription drugs are exempt or taxed at a reduced rate in many states.
Sales for resale (a retailer buying inventory) are exempt with a resale certificate.
Some states run sales-tax holidays on clothing or school supplies at set times of year.
Services are often untaxed, though more states tax specific services each year.

Frequently asked questions

Is there a federal sales tax in the US?

No. Sales tax is set by states and localities. There is no nationwide sales tax, which is why combined rates differ from one address to the next.

Why is the sales tax different in the next town over?

Counties, cities, and special districts add their own rates on top of the state base. Crossing a jurisdiction line can change the combined rate even within the same state.

What is sales tax nexus?

Nexus is the connection that requires a business to collect tax in a state — created by physical presence or, since the 2018 Wayfair ruling, by exceeding an economic threshold of sales or transactions.

How do I find the pre-tax price from a total that includes tax?

Divide the total by (1 + the tax rate). For a 9% rate, divide the total by 1.09. The reverse sales tax calculator does this and also shows the tax portion.