Credit card processing and merchant services in Thornton, CO
Thornton runs its own sales tax. Of the 8.5% on a sale, 3.75 points belong to the city and 4.75 to the state, and Colorado adds its own surcharge cap and cash law.
Thornton is a home-rule city, and it uses that status to run its own sales tax. The city's tax brochure says it's authorized to administer its tax laws and collect its own sales and use taxes, so a Thornton business answers to the city for the local share and to the state for everything else.
The city's tax explainer puts the combined rate at 8.5%: 3.75% for Thornton, 2.90% for the state, 1.10% for RTD and the cultural facilities district, and 0.75% for Adams County. Of that, 4.75% is remitted to the state and 3.75% to the city. Picture a store with $40,000 a month in taxable sales. It collects $3,400 in tax, and $1,500 of that belongs to Thornton while $1,900 goes to the state.
Owners with a second store in Aurora will find the numbers familiar. Aurora's city tax is also 3.75%, and the Adams County part of Aurora comes to 8.50%, the same total as Thornton. Same rate, different collector, though. Each city takes its own share, so set your POS reports to split city tax by location, or neither city's return will match what you collected.
The Census Bureau estimated Thornton's population at 147,766 in July 2025, 4.2% above its April 2020 base.
State law adds two rules of its own. Colorado caps a credit card surcharge at 2% of the sale or your actual merchant discount fee, requires it as a separate receipt line, and bars it on cash, checks, debit cards and gift card redemptions. And a retail store taking payment in person generally has to accept cash. The Colorado page quotes the statutes.
Whether 2% is worth adding depends on how much of your volume runs on credit. A free statement review puts a number on your per-card cost, interchange-plus pricing keeps it visible every month, and our surcharging program handles the disclosures if you go ahead.
Rules that matter in Thornton
Thornton's self-collected 3.75% sales tax
Thornton is a home-rule city authorized to administer its own tax laws and collect its own sales and use taxes. The city lists a combined rate of 8.5%: 3.75% for the City of Thornton, 2.90% for the State of Colorado, 1.10% for RTD and the cultural facilities district, and 0.75% for Adams County.
Of the 8.5%, the 4.75% that isn't Thornton's is remitted to the state, and the city's 3.75% is remitted to Thornton.
Sources: City of Thornton, Thornton taxes explained; City of Thornton, Sales and use tax general information brochure
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Common questions
What is the sales tax rate in Thornton, Colorado?
8.5% in total, according to the city: 3.75% for Thornton, 2.90% for the state, 1.10% for RTD and the cultural facilities district, and 0.75% for Adams County. Thornton collects its own 3.75% and the state collects the rest, so watch both for rate changes.
Do I send Thornton city sales tax to the state?
No. Thornton is a home-rule city that administers and collects its own sales and use taxes, so its 3.75% goes to the city. The other 4.75%, made up of the state's 2.90%, the RTD and cultural facilities taxes and Adams County's 0.75%, goes to the state. Keep the two amounts apart in your sales reports.
Is Thornton's sales tax the same as Aurora's?
Partly. Both cities charge 3.75% as their own share, but the totals match only in the Adams County part of Aurora, which comes to 8.50%. Aurora's Arapahoe and Douglas county parts are at 8.00% and 8.75%. Each city collects its own tax, so a business with stores in both files with both. Our Aurora page has the details.
How much can a Thornton store add for credit card payments?
No more than 2% of the sale or your actual merchant discount fee, under Colorado law, shown as its own line on the receipt. Debit cards, cash, checks and gift card redemptions can't carry a surcharge at all. Pick the 2% option and the statute supplies your sign wording, which our Colorado page quotes in full.
Can a Thornton shop stop taking cash?
Usually not. Under C.R.S. 11-61-102, a retail store where someone takes payment in person has to accept U.S. currency, and each refusal can cost up to $250. One cash-taking register per address is enough, so a busy shop can route cash to a single till. Businesses selling mainly through automatic renewal contracts are outside the rule.
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Disclaimer: general information, not professional advice
This page is general educational information, not legal, tax, accounting or financial advice. Rules and rates vary by place and change, so confirm them with the official source and a qualified professional before you act. Full terms are in our Terms of Service.
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