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FAQ
Sales tax calculator FAQ
Short answers about the math, the 2025/2026 rate table, and what this tool will not do.
What is StateTaxAdd?
A static educational sales tax calculator and 2025/2026 rates guide. It runs in the browser. It does not call a paid tax API.
How do I calculate sales tax from a pre-tax amount?
Tax = amount × (rate ÷ 100). Total = amount + tax. Example: $100 in a 7.25% state is $7.25 tax and $107.25 total.
How do I reverse sales tax from a total?
Pre-tax = total ÷ (1 + rate ÷ 100). Tax = total − pre-tax. Example: $107.25 at 7.25% is $100 pre-tax.
What does “typical local combined rate” mean?
It is the Tax Foundation population-weighted average of local sales taxes plus the statewide base, as of January 1, 2026. It is not your city’s ordinance rate.
Why is this not Avalara-grade?
Live engines resolve ZIP+4, district overlays, product taxability, exemptions, marketplace rules, and sourcing. StateTaxAdd uses one static number per state (plus an optional local).
Do rates change during the year?
Yes. Locals change on election calendars and fiscal dates. Statewide bases change less often. Re-check the department of revenue before you charge customers.
Which states have no sales tax?
Delaware, Montana, New Hampshire, and Oregon have no general sales tax here. Alaska has no statewide rate but many local taxes.
Is Hawaii or New Mexico a sales tax?
They are often grouped with sales taxes, but Hawaii’s GET and New Mexico’s GRT have broader bases and can hit business-to-business receipts.
Does this include use tax?
No. Use tax is the companion tax when you buy without paying sales tax and then use the item in a taxing state. The math looks similar; the legal trigger is different.
Can I use this for invoices or filings?
No. It is not tax advice and not a substitute for registered tax software or a CPA. See the disclaimer.