Where Summalo's tax data comes from
Wrong tax data is worse than none, so every rate and rule in Summalo has a source and a date. This page says where the data comes from and what to expect.
Rates
State rates and local rates come from the tax agencies of the states and from the Streamlined Sales Tax Governing Board. Louisiana's local rates come from the parish tax administrators' association (LATA). ZIP codes and places come from GeoNames (CC BY 4.0). Rate tables are harvested on a schedule and checked for plausibility before they are published.
Rules
Clothing rules, food rules and tax-free days are read from official state pages and statutes. Every rule has a source link and an “as of” date. Rules that are not fully confirmed are marked as such, and the app and these pages say so.
Updates
Rates are checked every month and can be downloaded in the app; the list of downloads is signed so that only Summalo's own data is accepted. The service status page shows when each state last changed.
What we do not do
Summalo gives estimates, not tax advice. At the register, the receipt is what counts. The app does not send the photos or the prices you scan anywhere.
Exchange rates and barcodes
Exchange rates come from the European Central Bank. Barcode lookups use Open Food Facts (ODbL) and are off unless you switch them on.
Questions and answers
How current are the rates?
The rate tables are checked every month. The “as of” date on each state page shows the date of the rules.
Where can I see when data changed?
On the status page: it lists each state with the date its rates last changed.
What if a rate is wrong?
Write to us at the address in the legal notice. If you switch on sharing in the app, you can also suggest a local rate anonymously.
More guides
- US sales tax for visitors explained
- Tax refund for tourists in the USA: is there one?
- Sales tax on clothing by state: which states exempt it?
- States without sales tax: where shopping can be cheaper
- Tax-free weekends and sales tax holidays 2026 and 2027
- How to calculate the final price: sale, coupon and sales tax
These pages summarise the rules Summalo uses. They are estimates, not tax advice. At the register, the store's receipt is what counts. Summalo applies these rules to the tag you scan, offline.