2026–2027 Tax Deadline Calendar for Connecticut Individuals and Small Businesses
Federal, Connecticut and Access Health CT dates from now through January 2028, already adjusted for weekends and holidays. Filter for what applies to you and add any date to your phone or computer calendar.
Quarterly payroll tax return for employers. Also the due date for a FUTA deposit if your undeposited FUTA tax is over $500. If every deposit was on time, you have until Nov. 10.
Connecticut quarterly withholding reconciliation (DRS), unemployment tax and wage report (CT DOL, ReEmployCT) and CT Paid Leave contributions and wage report.
Fourth installment of 2026 estimated income tax for calendar-year C corporations (Form 1120 filers).
Open enrollment for 2027 runs Oct. 23, 2026 to Jan. 15, 2027. Sign up or change plans by Dec. 15 to be covered from Jan. 1.
Last 2026 installment for self-employed people and anyone whose withholding doesn’t cover their tax. You can skip it if you file your 2026 return and pay all tax due by Feb. 1, 2027.
25% of your required annual payment, bringing you to 100%. Pay in myconneCT.
If you enroll between Dec. 16, 2026 and Jan. 15, 2027, coverage starts Feb. 1, 2027. After today you need a qualifying life event to enroll.
Give employees their 2026 W-2s and file W-2s with Form W-3 with the Social Security Administration. Give contractors their 1099-NECs and file them with the IRS. For payments made after 2025, a 1099-NEC is generally required once you pay a contractor $2,000 or more in the year.
If every deposit was made on time and in full, you have until Feb. 10, 2027 to file these returns.
Connecticut annual withholding reconciliation with W-2s (CT-W3), plus the fourth-quarter CT-941, CT DOL unemployment report and CT Paid Leave report.
Calendar-year multi-member LLCs taxed as partnerships and S corporations file and send K-1s. File Form 7004 by today for an automatic 6-month extension (to Sept. 15).
To be taxed as an S corporation starting with calendar year 2027, file Form 2553 by today. If you file late, S treatment generally starts in 2028 unless you qualify for late-election relief.
Due the 15th day of the third month after year end. The pass-through entity tax is optional for tax years starting in 2024 or later and is elected on this return.
LLCs file the annual report online at Business.CT.gov between Jan. 1 and March 31 every year, starting the year after the LLC was formed. Fee: $80.
File and pay. Form 4868 gives an automatic extension to file (to Oct. 15), but not to pay. Also the first 2027 estimated tax payment.
File and pay in myconneCT. A CT-1040 EXT extends the time to file only, not to pay. First 2027 CT estimated payment is also due (25%).
Calendar-year C corporations file Form 1120 (or Form 7004 for a 6-month extension) and deposit the first 2027 estimated tax installment.
Quarterly federal payroll tax return. If every deposit was on time and in full, you have until May 10.
Connecticut quarterly withholding, unemployment and Paid Leave reports.
Calendar-year C corporations. Normally due May 15.
Form 1040-ES. C corporations also deposit their 2nd 2027 installment today.
CT-1040ES. Brings you to 50% of your required annual payment.
Quarterly federal payroll tax return.
Connecticut quarterly withholding, unemployment and Paid Leave reports.
Form 1040-ES. C corporations also deposit their 3rd 2027 installment today.
CT-1040ES. Brings you to 75% of your required annual payment.
Only if you filed Form 7004 by March 15.
Only if you filed an extension by April 15. Interest and penalties run on any tax that wasn’t paid by April 15.
Quarterly federal payroll tax return.
Connecticut quarterly withholding, unemployment and Paid Leave reports.
Fourth installment of 2027 estimated income tax for calendar-year C corporations.
Normally Jan. 15. The IRS hasn’t published its 2028 calendar yet; this date applies the weekend-and-holiday rule.
Calendar files include a reminder 7 days before each date. They work with Google Calendar, Apple Calendar and Outlook. Nothing is sent anywhere; the file is made in your browser.
How to use this calendar
- Weekend and holiday rule. When a federal due date falls on a Saturday, Sunday or legal holiday, the IRS treats it as on time on the next business day. Connecticut DRS and CT DOL use the same next-business-day rule for their returns. Dates marked "Moved" are already shifted.
- Fiscal-year businesses. These dates assume a calendar tax year (January to December). If your business uses a fiscal year, your return and estimate dates are different.
- Extensions give you more time to file, not to pay. Pay what you expect to owe by the original date to limit interest and penalties.
- Payroll deposits (monthly or semiweekly) aren’t listed. Your payroll provider usually handles them. Not sure if you’re on track? See our payroll cost calculator or the contractor vs. employee cost tool.
- Estimated taxes. Figure your payments with the quarterly tax calculator.
Dates are for calendar-year filers and were checked against official sources in October 2026. Always confirm with the IRS, CT DRS or your tax preparer before you file. Not tax advice.
Frequently asked questions
When are 2027 quarterly estimated taxes due?
For 2027, federal and Connecticut estimated payments are due April 15, June 15 and Sept. 15, 2027, and Jan. 18, 2028 (Jan. 15, 2028 is a Saturday and Jan. 17 is Martin Luther King Jr. Day). The last 2026 payment is due Jan. 15, 2027.
When is the 2026 tax return due?
Federal Form 1040 and the Connecticut CT-1040 are due Thursday, April 15, 2027. Partnerships and S corporations file by March 15, 2027, and calendar-year C corporations file Form 1120 by April 15, 2027.
When do W-2s and 1099-NECs have to go out?
Feb. 1, 2027, because Jan. 31 is a Sunday. That date covers giving W-2s to employees, filing them with the Social Security Administration, and sending 1099-NECs to contractors and the IRS.
When is the Connecticut LLC annual report due?
Connecticut LLCs file their annual report online between Jan. 1 and March 31 each year, starting the year after the LLC was formed. The fee is $80.
When is Access Health CT open enrollment for 2027?
Oct. 23, 2026 through Jan. 15, 2027. Enroll by Dec. 15, 2026 for coverage that starts Jan. 1, 2027. If you enroll from Dec. 16 to Jan. 15, coverage starts Feb. 1, 2027.
Sources and assumptions (updated Oct 2026)
- IRS Publication 509 (2026), Tax Calendars: irs.gov/publications/p509, and the 2027 early-release draft: irs.gov/pub/irs-dft/p509--dft.pdf (draft; dates checked Oct. 30, 2026)
- CT DRS, 2026 estimated tax due dates and CT-1040 filing rules: portal.ct.gov/drs; withholding (CT-941, CT-W3): portal.ct.gov/drs; pass-through and corporation due dates: portal.ct.gov/drs
- CT DOL, quarterly unemployment tax report due dates: portal.ct.gov/dol; CT Paid Leave contributions: ctpaidleave.org
- CT Secretary of the State, annual report fee and filing window: business.ct.gov; CGS 34-247k
- Access Health CT, 2027 open enrollment dates: accesshealthct.com
Questions? Talk them through with a Danbury tax preparer, free for 15 minutes.