# Can you look up sales tax by ZIP code?

> Can you look up the sales tax rate by ZIP code?

Only roughly with a 5-digit ZIP: one ZIP code can cross city, county and special district lines, so it can have more than one combined rate. The Washington Department of Revenue puts it plainly: "5-digit ZIP codes do not accurately correspond with tax rates or taxing jurisdictions." A ZIP+4 or, better, the street address identifies the jurisdictions; the Streamlined Sales Tax boundary files map 5- and 9-digit ZIP codes, and in some states addresses, to tax codes.

## Why a ZIP code is not a tax jurisdiction

ZIP codes are USPS mail-delivery codes, not tax boundaries. A city or special district boundary can run through one, so addresses with the same five digits can owe different local rates. Even 9-digit ZIPs are not always enough: Minnesota's rate calculator notes it "may not provide an accurate sales tax rate when a 9-digit zip code crosses city or county boundaries."

Rates themselves vary by state. Texas, for example, imposes a 6.25 percent state rate and local entities can add up to 2 percent, for a maximum combined rate of 8.25 percent.

## How the Streamlined Sales Tax files handle it

Each Streamlined member state publishes a boundary file that "generally identifies the tax codes (for each taxing jurisdiction) that apply to an address based on either the 5 or 9-digit zip code", and in some states the actual address, and a rate file with the rate of each tax code. So the precise lookup tries the address first, then the ZIP+4, and falls back to the 5-digit ZIP only when nothing more precise matches; that is the order the Olympus API uses.

## In the Olympus API

- `GET /v1/sales-tax/rates/address` matches the street address, then ZIP+4, then ZIP, and says which it used (`accuracy`).
- `GET /v1/sales-tax/rates/zip/{zip}` takes a ZIP+4 or 5-digit ZIP; a 5-digit ZIP that spans several jurisdiction sets is answered as `ambiguous`, with every candidate, not one guessed rate.
- Published states: CT, DC, GA, IA, IL, IN, KY, MA, MD, ME, MI, MN, ND, NE, NJ, NV, OH, OK, PA, RI, SD, TN, UT, VT, WI, WV, WY. Other states, including Texas, are answered as `unsupported`. It is a published-rate lookup, not a tax calculation; see [Is there an API for sales tax rates by address?](https://olympus.new-odyssey.com/answers/sales-tax-rate-api).

## Questions

### Is sales tax based on ZIP code?

No. It is based on the taxing jurisdictions (state, county, city, special districts) at the location, and a ZIP code can span several of them.

### How do I find the exact sales tax rate for an address?

Use the state's address-level or ZIP+4 lookup, or in Streamlined member states the SST boundary and rate files, and add up the rates of every jurisdiction that applies on the date of the sale.

## Sources

- Washington State Department of Revenue: [Information for online sellers using shopping carts](https://dor.wa.gov/information-transitioning-destination-based-sales-tax-online-sellers-using-shopping-carts)
- Minnesota Department of Revenue: [Sales tax rate calculator](https://www.revenue.state.mn.us/sales-tax-rate-calculator)
- Streamlined Sales Tax Governing Board: [Rate and boundary files](https://www.streamlinedsalestax.org/Shared-Pages/rate-and-boundary-files)
- Texas Comptroller of Public Accounts: [Sales and use tax](https://comptroller.texas.gov/taxes/sales/)

## Related

- [Is there an API for sales tax rates by address?](https://olympus.new-odyssey.com/answers/sales-tax-rate-api)
- [Sales tax rates by address, explained](https://olympus.new-odyssey.com/guides/sales-tax-rates-by-address)

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Published 2026-10-24, updated 2026-10-24 by New Odyssey. Canonical: https://olympus.new-odyssey.com/answers/sales-tax-by-zip-code