Colorado tax deadlines in 2026: filing dates and estimated payments
Deadlines that fall in calendar 2026: the 2025 return and the 2026 estimated payments. Different year? See Colorado 2025 →
Colorado deadlines in 2026
| 2025 individual return due | April 15, 2026 |
|---|---|
| Extended filing deadline | October 15, 2026 |
| Payment due | April 15, 2026, extension or not |
| Final 2025 estimated payment | January 15, 2026 |
| 2026 estimated payments | April 15, 2026 · June 15, 2026 · September 15, 2026 · January 15, 2027 |
Conforms to April 15 with an automatic 6-month extension to October 15 (no form required).
Colorado estimated tax payments in 2026
You expect to owe more than $1,000 in net Colorado tax for 2026 after subtracting withholding and credits.
| Q1 (2026 tax year) | April 15, 2026 |
|---|---|
| Q2 (2026 tax year) | June 15, 2026 |
| Q3 (2026 tax year) | September 15, 2026 |
| Q4 (2026 tax year) | January 15, 2027 |
| Voucher | Form DR 0104EP |
| Underpayment safe harbor | Required annual payment is the smaller of 70% of actual net Colorado tax, 100% of prior-year net Colorado tax (only if prior-year federal AGI was $150,000 or less, $75,000 MFS), or 110% of prior-year net Colorado tax; farmers/fishermen (2/3 of income) 50% of actual net tax. |
| Pay online | colorado.gov |
Four equal installments; if the due date falls on a Saturday, Sunday or legal holiday payment is due the next business day. Farmers/fishermen who file and pay in full by March 1 are excepted from penalty. Underpayment penalty computed on DR 0204. The Department strongly recommends paying online via Revenue Online (no login required).
Source: tax.colorado.gov and tax.colorado.gov, read September 3, 2026. “Estimated tax payments are due in four equal installments on the following dates. April 15 (first calendar quarter) June 15 (second calendar quarter) September 15 (third calendar quarter) January 15 (fourth calendar quarter)”
All 51 jurisdictions in one table: state estimated tax payment dates for 2026.
Colorado extensions
Every state's rule in one table: which states accept the federal extension in 2026.
| Does Colorado accept the federal extension? | Not needed. The state extends everyone automatically. |
|---|---|
| Original due date | April 15, 2026 |
| Extended due date | October 15, 2026 |
| Payment | Still due April 15, 2026. The extension is to file, not to pay. 90% of the tax liability must be paid by April 15 to avoid penalties; any remaining balance is subject to interest only. |
| How to get it | Nothing to file; pay any balance through Revenue Online or with Extension Payment Form DR 0158-I by April 15. |
DR 0158-I is a payment voucher only; the federal Form 4868 is irrelevant to the Colorado extension.
Source: tax.colorado.gov, read September 3, 2026. “There is no form to fill out to notify the Department of Revenue that you are taking the extension, however, there is no extension for tax due.”
Federal deadlines in 2026
| 2025 Form 1040 | April 15, 2026 · extension October 15, 2026 |
|---|---|
| 2025 S-corp (1120-S) & partnership (1065) | March 16, 2026 |
| 2025 C-corp (Form 1120) | April 15, 2026 |
| 2026 federal estimated payments (1040-ES) | April 15, 2026 · June 15, 2026 · September 15, 2026 · January 15, 2027 |
Source: IRS Publication 509 and Form 1040-ES instructions, irs.gov.
Frequently asked questions
When are Colorado state taxes due in 2026?
Your 2025 Colorado individual income tax return is due April 15, 2026. If that date falls on a weekend or legal holiday, the deadline moves to the next business day. An extension moves the filing deadline to October 15, 2026, but any tax owed is still due on the original date.
When are Colorado estimated tax payments due in 2026?
Colorado estimated payments for the 2026 tax year are due April 15, 2026, June 15, 2026, September 15, 2026, January 15, 2027. Use Form DR 0104EP or pay online. The final installment for 2025 was due January 15, 2026.
Does Colorado accept the federal extension?
Not needed. The state extends everyone automatically. The extended filing deadline is October 15, 2026, and tax is still due by April 15, 2026.
Does a Colorado extension give me more time to pay?
No. An extension extends the time to file, not to pay. To avoid penalties and interest, pay what you expect to owe by April 15, 2026.
Dates are the statutory deadlines that fall in 2026 and move to the next business day when they land on a weekend or holiday. Each section links to the source it was checked against. Always confirm with the Colorado tax agency or the IRS before relying on a date. This is general information, not tax advice.