The deadline for 2025 individual income tax returns that were extended in April is Oct. 15. New York and New Jersey state returns are due the same day. An extension only delays filing, not payment, so if you still owe tax, interest and penalties have been accruing since April 15. Once you are more than 60 days late, the minimum failure-to-file penalty is the lesser of $510 or the full amount of tax owed.
Quite a few people filed an extension in April because they "didn't have time." That extension ends Thursday, Oct. 15. Two weeks remain.
This applies to anyone who extended their 2025 individual income tax return (Form 1040). New York and New Jersey state returns are also extended six months, in line with the federal return, so Oct. 15 is the deadline for them as well. Every year, some people take care of the federal return, forget the state return and receive a notice.
An Extension Is Not a Payment Extension
This is the most common misunderstanding. An extension only gives you permission to file your paperwork late, not to pay late. The payment deadline for 2025 taxes was April 15 of this year. If you did not pay in full by then, interest and late-payment penalties have been building since that day.
Conversely, if you paid a generous estimated amount in April, you face no extra cost as long as you file the paperwork on time now. If you are self-employed or a freelancer whose income is settled at the end of the year, the way to stop interest is to run the numbers now and send in any shortfall with your return.
How Much Does Filing Late Cost?
Two separate penalties apply. The failure-to-file penalty is 5% of the unpaid tax per month, up to 25%. Even one day late counts as a full month. The failure-to-pay penalty is 0.5% per month, also capped at 25%. In months when both apply, the failure-to-file penalty is reduced by the amount of the failure-to-pay penalty.
A minimum applies once you are more than 60 days past the deadline. For 2025 returns, it is the lesser of $510 or the full amount of unpaid tax. If you underpaid by $100, the minimum is $100; if you still owe $2,000, the penalty starts at $510. That means putting off a task that takes less than a minute can end up costing you $500 more.
If you owe no tax and are due a refund, no penalty applies. However, your right to claim a refund expires three years after the filing deadline. If you let it sit for years thinking, "I'm getting the money back anyway," you end up leaving the money with the U.S. Treasury.
If You Can't Afford to Pay
Even if you don't have the money to pay right now, it is better to file. The difference between 5% a month and 0.5% a month is tenfold. If you file and apply for an installment plan through your IRS online account, the failure-to-pay penalty rate drops further once the plan is approved. State governments also run their own installment programs.
Electronic filing will not stay open forever, either. Each year in mid-to-late November, the IRS temporarily shuts down its individual e-file system to prepare for the next filing season. After that, you must file by mail on paper, and processing takes several months. Even if you have missed Oct. 15, it is best to finish filing electronically within November if possible.
If you have not yet chosen an accountant to handle your paperwork, this is the last week to do so. Many offices stop accepting clients after the first week of October. The Korean American Association of New York and Korean American organizations in New Jersey hold free tax consultations each season, and people whose income is below a certain threshold can use IRS-designated free filing assistance through Volunteer Income Tax Assistance (VITA) sites.