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How sales tax works (in the US)

US sales tax is layered. Most rates are the sum of:

  1. State rate — a single number per state (or zero, for the five no-sales-tax states: DE, MT, NH, OR, and AK at the state level).
  2. County rate — set by the county the address lies within.
  3. City / place rate — set by an incorporated city or town. Unincorporated addresses skip this layer.
  4. Special-purpose district rates — emergency services districts (ESD), municipal utility districts (MUD), fire control districts, transit authorities, and other ballot-approved overlays. These can stack: an address might be in two SPDs simultaneously.

A jurisdiction is the legal entity that levies one of these rates. Knowing the rate at an address means knowing which jurisdictions overlap that address — that’s what TaxQL resolves.

Effective dates. Rates change. Most quarterly; some monthly. The “rate at an address” is implicitly “the rate in effect today”; TaxQL exposes the past via the as_of parameter on supported states.

Full content coming soon.