October 15 is the last stop for 2025 tax returns. If you filed an extension in April, this is the date the IRS and New York State expect the finished return. Miss it, and the clock that matters most starts running: the late-filing penalty. The good news is that the fix is simple, the cost grows slowly at first, and a lot of it can often be removed. This guide covers what happens if you miss the October 15 tax deadline, what it costs, and how to file late returns (including 2024 and earlier) the right way.
The short version: If you miss the October 15, 2026 extension deadline and you owe tax, the IRS failure-to-file penalty adds 5% of the unpaid tax for each month or part of a month you are late, up to 25%, on top of the 0.5% monthly late-payment penalty and interest that have been running since April 15. New York charges a matching 5% per month. If you are owed a refund, there is no late-filing penalty at all. Either way, file as soon as you can. E-file stays open after October 15, so a late return does not have to go on paper.
The deadline in plain English
April 15, 2026 was the deadline to file your 2025 return and pay what you owed. Filing Form 4868 with the IRS (and Form IT-370 with New York, if you file there) moved the filing deadline to Thursday, October 15, 2026. It never moved the payment deadline. Anything you owed in April has been collecting a late-payment penalty and interest since then.
October 15 is the end of the line for most people. There is no second extension. The main exceptions are taxpayers in federally declared disaster areas, who sometimes get extra time automatically, and members of the military serving in a combat zone.
What it costs to file after October 15
Here is what applies when you owe tax and the return comes in late.
| Charge | Federal (IRS) | New York State |
|---|---|---|
| Late filing | 5% of unpaid tax per month or part of a month, max 25% | 5% of unpaid tax per month or part of a month, max 25% |
| Minimum if more than 60 days late | $525 or 100% of the tax due, whichever is smaller | $100 or 100% of the tax due, whichever is smaller |
| Late payment | 0.5% of unpaid tax per month, max 25% | Also charged, monthly, on the unpaid balance |
| Interest | On unpaid tax and penalties, compounded daily | On unpaid tax, compounded daily |
Two details are worth knowing. First, when both federal penalties apply in the same month, the IRS reduces the late-filing penalty by the late-payment amount, so the combined charge is 5% a month, not 5.5%. Second, the late-filing penalty maxes out after five months, but the late-payment penalty and interest keep going until the balance is paid.
A quick example. Say you owe $4,000 on your 2025 return and file on December 20 instead of October 15. That is three months or part-months late, so the late-filing and late-payment penalties for those months add about 15% of $4,000, or $600, before interest. File by November 15 instead and it is about $200. Every month counts, which is why the honest advice is boring: file now, even if you cannot pay yet.
Can you still e-file after October 15?
Yes. The IRS keeps e-file open for 2025 returns until late December 2026. A return e-filed after October 15 is still late, but it is processed faster and you get confirmation that it arrived. Tax professionals can also e-file returns for the two prior years, so a missing 2024 return can usually go in electronically too. Older returns go on paper.
If you are owed a refund
There is no late-filing penalty when the IRS owes you money, because the penalty is a percentage of tax you owe, and you do not owe any. The catch is the refund deadline. You generally have three years from the original due date to claim it. Your 2025 refund is safe until April 2029. A 2023 refund expires on April 15, 2027. After that, the money stays with the Treasury for good.
Plenty of people put off filing because they assume they owe. If you had a W-2 job with normal withholding, there is a real chance you are actually owed money.
Cannot pay what you owe? File anyway
The late-filing penalty is ten times bigger than the late-payment penalty (5% a month versus 0.5%). So if you can file but cannot pay, filing on time and paying later is far cheaper than doing neither.
Once the return is in, the IRS has payment options:
- Short-term payment plan: up to 180 days to pay in full, with no setup fee.
- Long-term installment agreement: monthly payments, available online for most people who owe $50,000 or less in combined tax, penalties and interest.
- Penalty relief requests: covered in the next section.
New York State offers its own installment payment agreements through an Online Services account.
Can late-filing penalties be removed?
Often, yes.
- First-time abatement (IRS): if you had no penalties in the three prior tax years, have filed all currently required returns, and have paid or arranged to pay what you owe, the IRS will usually remove the late-filing and late-payment penalties for one year. You have to ask for it. It is not automatic.
- Reasonable cause: serious illness, a death in the family, a natural disaster, or records destroyed in a fire or flood can qualify, at both the IRS and New York State, if you acted responsibly once the problem passed.
Interest generally cannot be removed, except where the penalty it was charged on is removed. A tax professional can request abatement for you once the return is filed.
Behind on 2024 or earlier years too?
Late 2025 taxes rarely travel alone. If you also skipped your 2024 return or earlier years, the same rules apply to each year: penalties stop growing once the return is filed, refunds expire three years after each year's due date, and old years can be filed even without every original document.
Do not wait for the IRS to do it for you. If you do not file, the IRS can prepare a "substitute for return" using only the income it knows about, with none of your deductions, credits or dependents. The bill on a substitute return is almost always higher than the real one.
What you need to file a late return
- W-2s, 1099s and any other income forms for the year
- Last year's return, if you have it
- Any letters from the IRS or New York State
- Records for deductions you plan to claim (business expenses, mortgage interest, childcare, charitable gifts)
Missing forms are not a dead end. A tax professional can pull your IRS wage and income transcript, which lists the W-2s and 1099s reported under your Social Security number, for the current year and several years back. If you run a business and your books are behind, start with catch-up bookkeeping so the return is built on real numbers. Our tax documents checklist has the full list.
Filing late taxes in Westchester and NYC
London's Tax Services prepares and files late, extended and past-due federal and New York returns for individuals and small businesses from our office at 75 South Broadway in White Plains, serving Westchester County, the Bronx and New York City. We file the return, set up a payment plan if you need one, and request penalty abatement when you qualify.
If you are still sitting on your 2025 return, there is time before October 15. If you already missed it, the next best day to file is today. Book a free 15-minute call or call (646) 917-7714, and we will tell you what we need, what it will cost and how fast we can file.
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