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TaxQL Docs

Effective dates

Sales tax rates have effective dates. A jurisdiction announces a rate change months in advance; we load the new file as soon as it’s published; the new rate takes effect on its effective_from date.

Refresh cadence. State DoR publications are pulled daily. The load lands well before the effective date in most cases.

The as_of parameter. Pass as_of=YYYY-MM-DD to query the rate in effect on a specific date. Required when:

  • Recomputing tax for a refund or return at the rate that was effective when the original transaction happened
  • Auditing historical tax payments against current rates
  • Comparing rate changes across periods

effective_from and effective_to are returned on each row when the state’s rate data carries effective-period detail. They bound the period the row’s rate applies to:

row.effective_from   # date(2026, 4, 1) — Q2 starts
row.effective_to     # date(2026, 6, 30) — Q2 ends

States that store rates as a current snapshot only (NM, MO, IL, CO, LA, AL, AZ, AK at the state level) return the current rate regardless of as_of; historical queries against them are unsupported until those publications are backfilled.

Pre-history queries. When as_of predates the earliest loaded period for the state, the API falls back to the oldest available row and logs a warning internally. The response is still returned; ops is alerted to the coverage gap.

Full content coming soon — including the per-state rate-publishing schedule (which quarters land when).