Nobody misses a tax deadline on purpose. It happens because the dates are spread throughout the whole year, some of them quietly shift when they land on a weekend, and the date that applies to your business is often not the one that applies to your personal return. Plenty of people who know April 15 by heart have still walked right past March 15.
So here is a plain-English calendar for 2027, month by month, with federal dates first and New York items after. It’s written for calendar-year filers, which covers most individuals and small businesses we work with across Suffolk County. One thing to keep straight: returns you file in 2027 are for the 2026 tax year, while the estimated payments you make in 2027 are mostly for 2027 income.
Why do a few 2027 dates look odd
When a deadline lands on a Saturday, Sunday or federal holiday, it moves to the next business day. 2027 has a handful of these. January 31 is a Sunday, so year-end employer reporting slides to Monday, February 1. July 31 and October 31 are weekend days too, which pushes two payroll filings to August 2 and November 1. May 15 is a Saturday, which moves the nonprofit filing date to May 17. The dates below already reflect all of that.
January and February: Year-end paperwork
- Friday, January 15: Fourth-quarter 2026 estimated tax payment. This one is for the self-employed, landlords, investors, and anyone else who pays quarterly instead of through a paycheck.
- Monday, February 1: W-2s and 1099-NECs must reach your workers and contractors and be filed with the government. From 941 to the fourth quarter and Form 940 for federal unemployment tax are also due, with a few extra days available if every deposit was made on time.
If you paid contractors last year and don’t have their W-9s on file, February is a bad time to find out. Start chasing them in December.
March: The one people forget
- Monday, March 15: S corporations, partnerships and multi-member LLCs file their returns (Forms 1120-S and 1065) and send K-1s to their owners or file an extension. This is also the cutoff to elect S corporation status for the full year and, for New York pass-through entities, the deadline to opt into the Pass-Through Entity Tax if it makes sense for you.
- Wednesday, March 31: Electronically filed 1099-MISC, 1099-INT and 1099-DIV forms are due to the IRS.
March 15 catches more people than any other date. It arrives a full month before April 15, and the late-filing penalty for partnerships and S corporations is charged per owner, per month, so it adds up fast.
April: The big one
- Thursday, April 15: Individual returns (Form 1040), calendar-year C corporations, sole proprietors and trusts. The same day brings the first-quarter 2027 estimated payment, the last chance to make 2026 IRA and HSA contributions, and the deadline to request a six-month extension. New York personal income tax returns follow the same date.
- Friday, April 30: Form 941 for the first quarter.
A reminder we repeat every year: an extension gives you more time to file, not more time to pay. If you owe, interest and late-payment penalties start running on April 15 when the return is finished. A reasonable estimate sent with your extension keeps that bill small.
May through August: The quiet stretch
- Monday, May 17: Form 990 for calendar-year nonprofits.
- Tuesday, June 15: Second-quarter estimated tax payment.
- Monday, August 2: Form 941 for the second quarter.
Summer is the best time for a mid-year check. Compare your income so far to last year’s. If it’s running well ahead, your estimated payments may be too low, and an underpayment penalty is much easier to prevent in July than to explain in April.
September through December: Extensions end, planning begins
- Wednesday, September 15: Third-quarter estimated payment, and the extended deadline for S corporation and partnership returns.
- Friday, October 15: Extended individual returns and most extended C corporation returns. There is no second extension after this.
- Monday, November 1: Form 941 for the third quarter.
- Wednesday, December 15: Fourth-quarter estimated payment for calendar-year C corporations.
- Friday, December 31: The last day for most year-end moves: retirement contributions, equipment purchases you want to deduct this year, charitable gifts, and required minimum distributions for retirees.
Your individual fourth-quarter 2027 estimate falls in January 2028, and we’ll post the exact date when we update this calendar next year.
Don’t treat October 15 as a finish line you can drift toward. Anyone on extension who hasn’t gathered their paperwork by September is in for a rough few week.
New York dates to add to your calendar
Federal deadlines are only half the picture on Long Island. New York adds its own.
- Sales tax: Quarterly filers send their returns by the 20th of the month after the quarter closes. In 2027 that means Monday, March 22, Monday, June 21, Monday, September 20 and Monday, December 20. The first two move because the 20th falls on a weekend. Monthly filers are due on the 20th of every month. Your filing frequency is assigned to you, so confirm it in your NY Online Services account.
- NYS-45: Quarterly withholding and unemployment reporting generally follows the same rhythm as your federal 941s: end of April, early August, early November and the end of January.
- Pass-Through Entity Tax election: March 15, as noted above.
- Personal income tax: April 15.
Four habits that keep you out of trouble
1. Set reminders two weeks early. A reminder on the due date is just a warning that you’re already late. Two weeks gives you time to find the missing 1099 or the bank statement that never arrived.
2. Know your safe harbor for estimates. In general, paying at least 90% of this year’s tax, or 100% of last year’s (110% if your adjusted gross income was over $150,000), keeps you clear of the underpayment penalty. It’s a simple target when your income is unpredictable.
3. Keep the books current all year. Returns go quickly when the records are clean. If your QuickBooks file is a mess, cleanup in the fall is far cheaper than scrambling in March.
4. Watch disaster relief. When a storm or other federally declared disaster hits, the IRS can postpone deadlines for affected areas. Check irs.gov rather than assuming a date has moved.
Let us carry the calendar
If reading this made your stomach drop a little, you’re in good company. Most of our clients didn’t want to become experts on filing dates. They wanted to know if someone else was watching them.
That’s the job. We handle payroll filings, quarterly estimates, entity returns and, when something goes sideways, IRS notices and resolution. Every service is quoted upfront, so there are no surprise bills at the end.
Book a free consultation and we’ll go through your dates together.
Dates reflect IRS and New York guidance as reviewed in November 2026 and apply to calendar-year filers. Deadlines can change and your situation may differ, so confirm against IRS Publication 509 or with a CPA before relying on any date. We update this calendar every year.
