Colorado sales tax due dates fall on the 20th day of the month following each reporting period, whether you file monthly, quarterly, or annually. If the 20th lands on a weekend or holiday, the deadline moves to the next business day. Miss it, and the penalty starts at the greater of $15 or 10% of the tax owed, with interest running on top.1Department of Revenue – Taxation. Tax Topics – Penalties and Interest
Which Filing Schedule Applies to You
The Department of Revenue assigns your schedule based on how much state sales tax you collect in an average month. After you register, the Department tells you which frequency you’ve been placed on. Collections can shift you between schedules over time.
- Monthly filing: $600 or more per month in state sales tax collected.
- Quarterly filing: more than $15 but less than $600 per month.
- Annual filing: $15 or less per month, and only if you request it from the Department.
Annual filing isn’t automatic even if you qualify by volume. You have to ask for it.2Department of Revenue – Taxation. Sales Tax Filing Information
The Deadlines for Each Schedule
Monthly
Twelve returns, twelve deadlines. Sales tax collected in January is due February 20. February collections are due March 20. And so on through the calendar.2Department of Revenue – Taxation. Sales Tax Filing Information
Quarterly
Four returns a year, each covering a calendar quarter:
- January through March: due April 20
- April through June: due July 20
- July through September: due October 20
- October through December: due January 20 of the following year
Annual
All sales tax collected from January 1 through December 31 goes on a single return, due January 20 of the following year.2Department of Revenue – Taxation. Sales Tax Filing Information
When the 20th Falls on a Weekend or Holiday
If the due date is a Saturday, Sunday, or state or federal holiday, the deadline shifts to the next business day, and a return filed then counts as on time. This applies to every filing frequency.3Department of Revenue – Taxation. Individual Income Tax – Due Dates and Filing Extension
Watch the calendar around Memorial Day, Labor Day, Juneteenth, and Martin Luther King Jr. Day, since those are the ones most likely to push the 20th forward. Paper returns need a postmark by the due date to count as timely.
What a Late Return Costs
The penalty for failing to file or pay on time is the greater of $15 or 10% of the unpaid tax, plus an additional ½% for each month the tax remains unpaid. The total penalty caps at 18% of the tax owed.1Department of Revenue – Taxation. Tax Topics – Penalties and Interest
Interest is separate from the penalty. Colorado sets the rate each year based on the prime rate plus three percentage points, rounded to the nearest whole percent. For 2026, the regular interest rate is 11%. A discounted rate of 8% applies if you voluntarily correct an underpayment or pay within 30 days of receiving a notice from the Department.1Department of Revenue – Taxation. Tax Topics – Penalties and Interest
Skipping a return entirely doesn’t buy you time. If you don’t file, the Department will file one for you using estimated figures and bill you for the result. That estimate stays on your account until you replace it with an actual return.2Department of Revenue – Taxation. Sales Tax Filing Information
Home-Rule Cities Have Their Own Due Dates
Filing a state return does not satisfy your obligations to Colorado’s home-rule cities. Denver, Aurora, Colorado Springs, Boulder, and dozens of other jurisdictions administer their own sales tax, set their own rates, decide what’s taxable, and pick their own filing deadlines. If you make sales in a home-rule city, you must register with that city and file returns directly to it.4Department of Revenue – Taxation. Local Government Sales Tax
Home-rule due dates don’t always match the state’s 20th-of-the-month schedule, so build a separate calendar for each city where you do business. The Sales and Use Tax System (SUTS) portal lets you file returns for the state, state-collected local jurisdictions, and participating home-rule cities in one place. Not every home-rule city participates, but the roster keeps growing.5Department of Revenue – Taxation. Sales and Use Tax System (SUTS)
Filing the Return
The state return is Form DR 0100, the Colorado Retail Sales Tax Return. Before you file, pull your gross sales for the period, your exempt sales (wholesale transactions, sales to tax-exempt organizations, out-of-state deliveries), and any applicable deductions. The form walks you through subtracting exemptions from gross sales to get your net taxable amount, then calculates tax due for the state and any state-collected local jurisdictions.6Department of Revenue – Taxation. DR 0100 – Retail Sales Tax Return
Most filers use Revenue Online, the Department’s electronic portal. You enter your figures, the system calculates what you owe, and you pay by electronic funds transfer or credit card. Save the confirmation number after you submit. If you file on paper, mail the completed DR 0100 to Colorado Department of Revenue, Denver, CO 80261-0013, postmarked by the due date.7Colorado Department of Revenue. Colorado Retail Sales Tax Return
One thing to double-check: the jurisdiction codes on your return. Misidentifying a local jurisdiction means underpaying one and overpaying another, which sends you back through an amended return to fix.
One More Change for 2026
Colorado used to let retailers keep a 4% service fee on the sales tax they remitted, capped at $1,000 per filing period. That fee is gone as of January 1, 2026, under House Bill 25B-1005. You now remit 100% of the state sales tax you collect on every return.8Department of Revenue – Taxation. Service Fee The due dates haven’t changed — just the amount you send in.