Colorado

Corporate income tax

C Corporation Income Tax Return (DR 0112) and payment are due the 15th day of the 5th month following the close of the tax year (per the 2025 DR 0112 instructions, the Due Date Guide and the Corporate Income Tax Guide).

Extension. Automatic 6-month filing extension (November 15 for calendar-year filers); no extension for payment (use DR 0158-C for extension payments)

Partnerships and S corporations

SALT Parity Act (SB 22-124) allows partnerships and S corporations to make an annual, irrevocable election to pay Colorado income tax at the entity level for tax years 2022 onward (retroactive elections were allowed for 2018-2021). S corps are otherwise not taxed at entity level.

Sales and use tax

Due date. Returns (DR 0100) and payment due the 20th day of the month following the filing period (monthly, quarterly, annual and seasonal filers); next business day if the 20th falls on a weekend/holiday.

Filing frequency. Determined by the amount of state and state-administered sales tax collected per month (averaged over 12 months); the Department reviews annually and can move filers to more frequent schedules.

Thresholds. Effective April 14, 2026 (Rule 39-26-109): $50 or less per month may file annually (due January 20); less than $1,100 per month may file quarterly; $1,100 or more per month must file monthly. (Previously $15 / $300.) Wholesalers with liability of $600/year or less may file annually.

Prepayments. No prepayment/accelerated schedule; businesses paying more than $75,000 per year in state sales tax must remit by EFT.

Notes

Two recent changes: the C-corporation due date is now the 15th day of the 5th month (May 15) with extension to November 15, and sales-tax filing-frequency thresholds rose to $1,100/$50 per month effective April 14, 2026. Colorado has no franchise tax; the Periodic Report is filed with the Secretary of State and was not chased.