(NewsNation) — Tax season is here, which means taxpayers have until April 15 to file last year’s income. But what happens if you don’t file your taxes?

The Internal Revenue Service (IRS), which processes tax returns, grants extensions in some cases, but you must apply for the extension by April 15, the same day returns are due.

For those who don’t file — and don’t request additional time — you will face a “failure to file” penalty from the IRS. That means you will have to pay a percentage of the taxes you didn’t pay on time.

The IRS suggests filing all past-due returns regardless of whether you can pay in full if you owe taxes.

2025 tax season: Failure to file penalty

The failure to file penalty is based on how late you file. For every month you’re overdue, the IRS will charge you 5% of your unpaid taxes as a late fee. The penalty caps at 25%, according to the IRS.

The IRS also charges interest on penalties.

There are minimum late fee penalties for returns more than 60 days late.

Aside from fees, it is illegal for anyone who makes the minimum income to fail to file a tax return.

2025 tax season: Important dates

The 2025 tax season has officially started, and there are important deadlines you need to know.

Here are the key dates for the 2025 tax filing season:

• Tax season officially began Monday, Jan. 27.
• The federal tax filing deadline, Tax Day, is Tuesday, April 15.
• If you need more time to file your taxes, you can request an extension, but you need to do so by April 15. That will give you an extra six months, until October 15, to file without penalties.
• The IRS generally issues refunds within 21 days for taxpayers who file electronically and choose direct deposit. Paper returns take longer.