State-specific notes

Most callers can use the same GET /v1/tax/{state} request everywhere. This page calls out the states where the input mode you choose changes the precision of the answer, and any quirk worth knowing when you read a rate.

Texas

Use address mode whenever you have a street address — it resolves Special Purpose Districts (SPDs) that a ZIP alone can miss, especially in border ZIPs where a city boundary cuts through. ZIP mode is fine for low-stakes lookups but can be ambiguous where a ZIP spans more than one taxing jurisdiction.

Florida

Both address mode (preferred) and lat/lng mode resolve to rooftop accuracy from the state’s published Master Address List. ZIP mode falls back to a ZIP-level answer with a lower confidence.

California, Washington, New Mexico

Lat/lng mode is a first-class input here — a coordinate resolves directly to the applicable jurisdiction. Address mode works too; use whichever input you have.

SST states

The 23 Streamlined Sales Tax states publish ZIP+4 boundary data. Passing a full ZIP+4 (zip="12345-6789") resolves to a single boundary answer. With a 5-digit ZIP only you get the state’s common rate, but a boundary ZIP may not resolve to one answer — pass an address or ZIP+4 to disambiguate.

These states are: AR, GA, IA, IN, KS, KY, MI, MN, NC, ND, NE, NJ, NV, OH, OK, RI, SD, TN, UT, VT, WI, WV, WY.

New York

Both address mode and ZIP mode work. A ZIP that straddles locality boundaries can be ambiguous; use address mode for a single answer.

Flat and no-tax states

Some states have a single state-wide rate with no local component — Delaware, Montana, New Hampshire and Oregon collect no sales tax (0%); a handful of others have no local jurisdictions on top of the state rate. For these, every input mode returns the same answer.

Current state coverage

New states and refinements ship regularly. The API Reference and the live spec at api.taxql.com/openapi.json always reflect the current supported set.