when is the last day you can send in federal income tax forms

The last day to send in federal income tax forms for the 2024 tax year is April 15, 2025. If you file an extension using Form 4868, you can extend the filing deadline until October 15, 2025. However, any taxes owed must still be paid by April 15, 2025, to avoid penalties and interest. If April 15 falls on a weekend or holiday, the deadline is typically extended to the next business day. For mailing paper returns, the postmark date must be on or before April 15, 2025, to be considered timely.