For the 2026 tax year, W-2s and 1099-NECs are due February 1, 2027, partnership and S corporation returns March 15, 2027, and individual, C corporation and Colorado individual returns April 15, 2027. Extended returns are due September 15, 2027 for partnerships and S corporations and October 15, 2027 for individuals and C corporations.
The dates below cover the 2026 tax year, meaning the returns you file in 2027, plus the estimated payments for 2027 itself. They assume a calendar-year taxpayer. If your business uses a fiscal year, the same rules apply, counted from the end of your fiscal year.
One rule explains most of the odd-looking dates. When a federal due date falls on a Saturday, Sunday or legal holiday, the deadline moves to the next business day, as IRS Publication 509 explains. That is why several familiar deadlines shift in 2027.
Key deadlines at a glance
| Date | What is due | Applies to |
|---|---|---|
| Tue, Dec 15, 2026 | Fourth-quarter 2026 estimated tax for calendar-year C corporations (federal and Colorado) | C corporations |
| Fri, Jan 15, 2027 | Fourth-quarter 2026 estimated tax (federal Form 1040-ES and Colorado DR 0104EP) | Individuals, self-employed owners |
| Mon, Feb 1, 2027 | W-2s to employees and the Social Security Administration; 1099-NECs to recipients and the IRS; fourth-quarter Form 941 | Employers and businesses paying contractors |
| Mon, Mar 15, 2027 | Federal partnership (Form 1065) and S corporation (Form 1120-S) returns, or Form 7004 extension | Partnerships, S corporations |
| Thu, Apr 15, 2027 | Federal Form 1040 and Colorado DR 0104, or extension; federal Form 1120 for C corporations; Colorado DR 0106 for partnerships and S corporations; first-quarter 2027 estimated tax | Individuals, C corporations, Colorado pass-through entities |
| Thu, Apr 15, 2027 | Business personal property declaration to the county assessor | Businesses owning equipment or furniture |
| Mon, May 17, 2027 | Colorado C corporation return (DR 0112) | C corporations |
| Tue, Jun 15, 2027 | Second-quarter 2027 estimated tax | Individuals, corporations |
| Wed, Sep 15, 2027 | Third-quarter 2027 estimated tax; extended federal Forms 1065 and 1120-S | Individuals, corporations, partnerships, S corporations |
| Fri, Oct 15, 2027 | Extended Form 1040, Colorado DR 0104 and DR 0106, and federal Form 1120 | Individuals, C corporations, Colorado pass-through entities |
| Mon, Nov 15, 2027 | Extended Colorado C corporation return | C corporations |
| Wed, Dec 15, 2027 | Fourth-quarter 2027 estimated tax for calendar-year C corporations | C corporations |
Individual deadlines
Your 2026 Form 1040 and your Colorado DR 0104 are both due Thursday, April 15, 2027. The IRS confirms the April 15 rule on its when to file page, and Colorado’s Due Date Guide sets the same date for the state return.
If you need more time, federal Form 4868 extends the filing deadline six months, to October 15, 2027. Colorado gives an automatic extension to the same date. Neither extends the time to pay, so estimate your balance and pay it by April 15.
Business return deadlines
Federal partnership and S corporation returns, and the K-1s that owners need for their own returns, are due Monday, March 15, 2027. A Form 7004 filed by that date extends them six months, to September 15, 2027, according to the Form 7004 instructions. Calendar-year C corporations file Form 1120 by April 15, 2027, or October 15, 2027 on extension.
Colorado’s schedule is slightly different. The state’s partnership and S corporation return, DR 0106, is due April 15, 2027, not March 15. Colorado allows six more months to file, but the Department’s partnership and S corporation filing page says at least 90% of the tax must be paid by the original due date to avoid penalties. That matters for businesses that elect to pay Colorado tax at the entity level. Colorado C corporation returns are due one month after the federal return.
Employer and information return deadlines
For 2026, employers must furnish Forms W-2 to employees and file them with the Social Security Administration by February 1, 2027, per the IRS instructions for Forms W-2 and W-3. Form 1099-NEC follows the same January 31 rule in the Form 1099-NEC instructions, so it also moves to February 1. For payments made in 2026, a 1099-NEC is generally required only when you pay a contractor $2,000 or more, up from $600.
Colorado wants its copy of W-2 and 1099 withholding statements by January 31 as well.
Quarterly federal payroll returns on Form 941 are due the last day of the month after each quarter, as the Form 941 instructions explain: April 30, July 31, October 31 and January 31. Colorado wage withholding returns follow their own schedule, quarterly, monthly or weekly depending on how much you withhold.
Estimated tax deadlines
If you earn income without withholding, such as business profit, rent or investment gains, you pay tax in four installments. The 2026 Form 1040-ES sets the 2026 dates as April 15, June 15 and September 15, 2026, with the last on January 15, 2027. Colorado uses the same dates.
For 2027, the first three installments fall on April 15, June 15 and September 15, 2027, following the same rule. The final 2027 installment falls in January 2028.
To avoid a federal underpayment penalty, your withholding and estimates generally need to cover the smaller of 90% of this year’s tax or 100% of last year’s. If last year’s adjusted gross income was over $150,000, the second test becomes 110%. Colorado’s version uses 70% of the current year, as its 2026 estimated tax form shows.
How to use this calendar
Pick the three or four rows that apply to you and put them on your own calendar now, with a reminder two weeks before each. For a business owner, the dates that cause the most trouble are not the April ones. They are February 1, because contractor 1099s need W-9s collected in advance, and March 15, because every owner’s personal return waits on the K-1s from the business return.
If you would like us to track these for you, our tax planning and preparation team builds each client’s deadlines into the engagement, and our payroll team handles the employer filings.
Common questions
Why are W-2s due February 1, 2027 instead of January 31?
January 31, 2027 falls on a Sunday. When a federal deadline lands on a weekend or legal holiday, it moves to the next business day, which is Monday, February 1.
Are Colorado partnership and S corporation returns due in March like the federal returns?
No. Colorado's return for partnerships and S corporations (DR 0106) is due April 15 for calendar-year filers, a month after the federal March 15 deadline. Many firms still prepare both together, because the federal return drives the Colorado one.
Can I skip the January 15, 2027 estimated payment?
For federal purposes, yes, if you file your 2026 return by February 1, 2027 and pay the entire balance with it. Otherwise, make the January payment to avoid an underpayment penalty for the fourth quarter.
Does an extension give me more time to pay?
No. Federal and Colorado extensions give you more time to file, not to pay. Tax owed is still due on the original deadline, and interest runs from that date on any unpaid amount.
What happens if a deadline is postponed for a disaster?
The IRS sometimes postpones deadlines for taxpayers in federally declared disaster areas. Postponements apply only to the areas named, and Colorado decides separately whether to match them, so check both announcements rather than assuming they cover you.