How to Verify a Colorado Resale Certificate: Revenue Online Steps

To verify a Colorado resale certificate, go to the Department of Revenue’s Revenue Online site, click “Verify a License or Certificate,” and enter the buyer’s Colorado sales tax account number and legal business name exactly as they appear on the buyer’s license. The system tells you in real time whether the account is active. Save the confirmation. A seller who runs this check and keeps the documentation earns a safe harbor: even if the Department later decides the sale was taxable, you’re relieved of liability for that transaction.¹

What to Get From the Buyer First

You need two things: the buyer’s Colorado sales tax account number and the exact legal business name registered with the Department. The account number is the first eight digits of the use account number printed on the buyer’s sales tax license. Copy both directly off the license. Minor differences in spelling or business structure will kick back a no-match result, so don’t work from what the buyer tells you verbally.

Colorado doesn’t issue a separate “resale certificate” the way some states do. The buyer’s Colorado sales tax license is itself the proof of authority to purchase for resale without paying sales tax.² A buyer may also complete a Department-issued exemption certificate or affidavit of exempt sale to document the transaction more formally, but the account number on the license is still what you’ll plug into the verification tool.

Running the Check on Revenue Online

State regulation directs sellers to colorado.gov/revenueonline and the link labeled “Verify a License or Certificate.”¹ Type in the account number and the business name as they appear on the license, and run the search. The tool queries the state database live and reports whether the account is current and valid at that moment. There’s no fee, and the whole thing takes under a minute.

Save or print the results page right away. That confirmation is what proves you checked, and it’s what you’ll need if an auditor ever asks.

Inspecting the License Instead

Online verification is the default under the regulation, but there’s an alternative: inspecting a physical copy of the buyer’s license or certificate. If you use this method, confirm the document is complete, that every field is filled in, and that the license hasn’t expired. Keep a copy in your file.¹

The online check is the more reliable of the two, because a printed license can be outdated or revoked without the buyer knowing. Revenue Online reflects the account’s status right now. For a large order or a new buyer, the extra certainty is worth the minute it takes.

Reading the Result

An active result means the buyer holds a valid Colorado sales tax license and can purchase for resale without paying sales tax, provided the goods are the kind the buyer would reasonably resell in the ordinary course of business. You can complete the sale tax-free.

An inactive, expired, or no-match result means the buyer has no valid exemption right now. Collect the full sales tax on the transaction. Colorado’s state rate is 2.9%, with city, county, and special district rates often added on top.³ Selling tax-free to a buyer whose account isn’t active puts the uncollected tax on you.

Because the tool reflects status on the day you run it, a license that verified fine six months ago may not verify today. That’s why the state expects you to check at or near the time of each sale, not once and forever.

Buyers From Other States

Plenty of Colorado sellers get resale claims from buyers who hold a sales tax license from another state but not from Colorado. You may accept an out-of-state resale license as documentation for an exempt sale, and you must keep a copy of it. If the license has no printed expiration date, or if the buyer gives you only a number rather than the physical document, you have to verify with the issuing state that the license is currently valid.⁴

Colorado also accepts the Multistate Tax Commission’s Uniform Sales and Use Tax Certificate, though not for claiming a resale exemption on a taxable service.⁴ Another option is to have the buyer complete a Department-issued exemption certificate and keep the completed form.

If a buyer has no sales tax license or exemption certificate from any state, collect the tax. That’s true even if the buyer says their own end customer holds an exemption. The verification burden sits with you as the seller.⁴

Repeat Customers

You don’t have to re-verify every order from the same buyer. Once you’ve confirmed a license is current and valid, that verification covers subsequent purchases from that buyer until the license expires, as long as nothing gives you reason to think it’s been revoked or suspended.¹ Red flags reset the clock. If a repeat buyer starts ordering products outside their line of business, or you hear the business has closed, run a fresh check before the next tax-free sale.

What to Keep, and For How Long

Colorado law requires sellers to keep invoices for goods purchased for resale, along with any other books and records needed to determine the tax owed, for at least three years, and to make them available to the Department during that period.⁵ A working exempt-sale file for each transaction should contain:

A screenshot, printout, or PDF of the Revenue Online confirmation showing the account was active on the date you checked.
A copy of the buyer’s sales tax license, exemption certificate, or out-of-state documentation.
The invoice or sales order showing what was sold, when, and for how much.

The Department ordinarily has three years from the date a return was filed to assess additional tax, and that window can extend by another year if a written proposed adjustment goes out before the deadline. It disappears entirely for fraudulent or unfiled returns.⁶ Holding onto records for four years gives you a comfortable buffer.

What Happens If You Skip the Check

Every Colorado retailer is liable for the sales tax that should have been collected on a transaction.⁷ If an audit finds you sold goods tax-free to a buyer whose account was invalid and you can’t show you verified it, you owe the uncollected tax. On top of that:

A penalty of the greater of $15 or 10% of the unpaid tax, plus an additional 0.5% for each month the tax remains unpaid, up to a combined maximum of 18%.⁸
Interest at 11% annually on unpaid tax balances for 2026, set each year based on the prime rate plus three percentage points and established by the commissioner of banking.⁹

Interest accrues from the date the tax was originally due, not from the date the audit finds the problem. Over years of unverified exempt sales, that compounds quickly.

The safe harbor is the flip side. A seller who followed the due diligence steps and kept the documentation has met the burden of proof, and the Department will not hold that seller liable for the uncollected tax on the transaction, even if the buyer turned out not to qualify.¹ That’s the whole reason to run the check: it moves the risk off your books and onto the buyer who misrepresented.

1
Colorado Secretary of State. Colorado Code of Regulations 1 CCR 201-4 – Documenting Exempt Sales
2
Colorado Department of Revenue – Taxation. Other License Types
3
Colorado Department of Revenue – Taxation. Sales Tax Guide
4
Colorado Department of Revenue. General Information Letter GIL-13-006
5
Justia Law. Colorado Revised Statutes Title 39 Section 39-26-116
6
Justia Law. Colorado Revised Statutes Title 39 Section 39-21-107
7
FindLaw. Colorado Revised Statutes Title 39 Section 39-26-105
8
Colorado Department of Revenue – Taxation. Tax Topics – Penalties and Interest
9
Colorado Division of Banking. Interest Rates Set by the Bank Commissioner