Colorado Business Tax Deadlines (2026)
Next: June 15, 2026 — Federal & Colorado Q2 Estimated Tax Payment
Next Deadline: June 15, 2026 — Federal & Colorado Q2 Estimated Tax Payment
Federal Tax Deadlines (2026)
| Form | Who Files | Due Date | Extension Deadline |
|---|---|---|---|
| Form 1040 (Schedule C) | Sole proprietors | April 15 | October 15 |
| Form 1065 | Partnerships, Multi-member LLCs | March 15 | September 15 |
| Form 1120-S | S-Corporations | March 15 | September 15 |
| Form 1120 | C-Corporations | April 15 | October 15 |
| Form 990 | Nonprofits | May 15 | November 15 |
| Estimated Taxes (Q1) | All | April 15 | — |
| Estimated Taxes (Q2) | All | June 15 | — |
| Estimated Taxes (Q3) | All | September 15 | — |
| Estimated Taxes (Q4) | All | January 15, 2027 | — |
Colorado State Tax Deadlines (2026)
| Tax Type | Due Date | Form/Filing | Notes |
|---|---|---|---|
| Individual Income Tax | April 15 | Form 104 | Flat 4.4% rate |
| Corporate Income Tax | April 15 | Form 112 | Flat 4.4% rate |
| S-Corp Return | March 15 | Form 106 | Composite filing available |
| Partnership Return | March 15 | Form 106 | Pass-through entity |
| Sales Tax (Monthly) | 20th of following month | DR 0100 via Revenue Online | State rate 2.9% |
| Retail Delivery Fee | Monthly with sales tax | Included in DR 0100 | $0.29 per delivery |
| Withholding Tax (Monthly) | Last day of following month | Via Revenue Online | Employers |
| Periodic Report | Annually | Filed with Secretary of State | Due on anniversary of formation |
| Estimated Income Tax (Q1) | April 15 | Form 104EP / 112EP | — |
| Estimated Income Tax (Q2) | June 15 | Form 104EP / 112EP | — |
| Estimated Income Tax (Q3) | September 15 | Form 104EP / 112EP | — |
| Estimated Income Tax (Q4) | January 15, 2027 | Form 104EP / 112EP | — |
Quarterly Estimated Tax Deadlines in Colorado
Colorado follows the federal estimated tax payment schedule:
Estimated payments are required if you expect to owe $1,000 or more in Colorado income tax.
Colorado-Specific Tax Requirements
Colorado has a flat income tax rate of 4.4% for both individuals and corporations, which simplifies calculations considerably. The state uses federal taxable income as the starting point for the state return, then applies Colorado-specific additions and subtractions. There is no separate franchise tax or gross receipts tax in Colorado.
Colorado's state sales tax rate is 2.9%, but the local tax landscape is notoriously complex. Colorado is a home-rule state, meaning many cities and counties administer their own sales taxes independently of the state. Denver, for example, collects its own sales tax separately. Businesses may need to register with and file returns for multiple jurisdictions. The economic nexus threshold is $100,000 in sales. Colorado also charges a Retail Delivery Fee of $0.29 per delivery made by a motor vehicle, which must be collected and remitted.
Colorado requires businesses to file a Periodic Report with the Secretary of State annually (due on the anniversary of formation). The filing fee is $10 for most entities. Colorado also participates in the Multistate Tax Commission and has relatively straightforward employer withholding requirements. Payroll withholding is due monthly or quarterly depending on the amount withheld.
What Happens If You Miss a Colorado Tax Deadline?
Colorado Department of Revenue
Get Your Books Ready Before Tax Season
Colorado's flat tax rate makes filing simpler than most states, but the patchwork of local sales tax jurisdictions can trip you up. Get your books in order so you can file clean returns across every jurisdiction.
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