If you file your taxes after the October 15 deadline (the extended deadline if you filed for an extension), you will face penalties and interest. The failure-to-file penalty is typically 5% of the unpaid taxes for each month your return is late, up to a maximum of 25%. If your return is more than 60 days late, the minimum penalty is either $510 (for 2025) or 100% of the tax due, whichever is less. Additionally, if you owe taxes and don't pay by the October deadline, a failure-to-pay penalty of 0.5% per month on the unpaid amount will accrue, along with daily interest based on the federal short-term rate plus 3%. The combined failure-to-file and failure-to-pay penalties cannot exceed 5% per month. Penalties are retroactive to the original filing date (typically April 15), so late payment penalties begin earlier than late filing penalties. If you miss the October deadline, it is best to file as soon as possible to minimize further penalties and interest. Filing late is usually better than not filing at all since you may still be eligible for refunds and to stop penalty growth. Some relief programs exist for reasonable cause or disaster situations, but the default penalties grow quickly with time after October 15.
In summary, filing your taxes after October results in significant financial penalties and interest, and you should file immediately to reduce them.
