When Can You File Taxes in Colorado?

Filing taxes in Colorado is a key responsibility for residents and businesses. Knowing important dates, deadlines, and potential penalties helps ensure a smooth process and avoids financial setbacks.

Earliest Filing Window

Colorado taxpayers can submit state income tax returns once the IRS begins accepting federal returns, typically in mid-to-late January. The state processes returns in coordination with federal filings, making it efficient to file both together.

E-filing is the fastest method, reducing errors and speeding up processing. Most tax software and professional preparers support electronic submissions as soon as the IRS system is live. Paper returns are accepted but take significantly longer to process, delaying refunds by weeks.

Filing early is beneficial, especially for those expecting a refund, as the Colorado Department of Revenue (CDOR) typically issues refunds within a few weeks. Taxpayers who owe can file early and schedule their payment for the due date, avoiding last-minute stress.

Income Thresholds

Not all Colorado residents must file a state income tax return. Filing requirements depend on total income, filing status, and income sources. The CDOR follows federal adjusted gross income (AGI) thresholds. For 2024 tax returns filed in 2025, single filers under 65 must file if they earn at least $14,600, while married couples filing jointly must file if their combined income is at least $29,200. These amounts are adjusted annually for inflation.

Even if income falls below these thresholds, filing may be beneficial to claim a refund for state tax withholding or refundable credits. Income from rental properties, self-employment, or investments may also require filing. Nonresidents and part-year residents must file if they earned income from Colorado sources, with tax obligations prorated based on in-state earnings.

Filing Deadlines

Colorado state income tax returns are due April 15, 2025, aligning with the federal deadline unless it falls on a weekend or holiday, in which case the deadline moves to the next business day.

Late payments begin accruing interest immediately after the due date. The state’s interest rate is typically the federal short-term rate plus three percentage points. Late payment penalties start at 5% of the unpaid amount for the first month, with an additional 0.5% added each month, up to 12%.

Extensions

Colorado grants an automatic six-month filing extension, moving the deadline to October 15, 2025. Unlike the federal extension, which requires Form 4868, the state does not require a separate request as long as the return is filed by the extended deadline. However, this extension applies only to filing, not payments. Any balance due must be paid by April 15 to avoid penalties and interest.

Taxpayers expecting to owe can submit an estimated payment using Colorado Form DR 0158-I for individuals or DR 0158-C for corporations. Payments can be made online through the Revenue Online portal or by mail. If at least 90% of the total tax liability is paid by the original deadline, the remaining balance avoids late payment penalties, though interest still applies.

Those facing financial hardship may qualify for a payment plan. Colorado offers structured installment agreements, but applying early is advised since approval is not guaranteed. Active military members serving in combat zones receive automatic extensions under federal and state laws, with deadlines based on deployment dates.

Refund Timing

Refund processing times depend on filing method, accuracy, and verification requirements. The CDOR typically issues refunds within 21 days for electronically filed returns, though some process in as little as a week. Paper returns take up to 12 weeks due to manual processing and mailing delays.

Taxpayers can check their refund status through the Revenue Online portal. Delays often result from errors, mismatched information, or claims for certain credits requiring additional review. Fraud prevention measures may also extend processing times. To avoid delays, ensure accuracy and opt for direct deposit over paper checks.

Penalties for Late Filing

Failing to file on time results in penalties that increase the longer the delay. Colorado imposes a late filing penalty of $5 or 5% of the unpaid tax, whichever is greater, for the first month past the deadline. Each additional month adds another 0.5%, up to 12%. If no tax is owed, there is no penalty for late filing, but taxpayers may miss out on refunds or credits.

Interest on unpaid taxes accrues immediately after April 15. The rate is based on the federal short-term rate plus three percentage points. Extended noncompliance may lead to tax liens or wage garnishments. Those unable to pay in full should consider a payment plan to minimize penalties and interest.