The Economic Times

2026 USPS postmark rule change: why IRS tax returns mailed April 15 may be late, penalties triggered, and safe filing steps explained

USPS postmark rules 2026 are creating real tax filing risks this year. Over 160 million Americans file taxes annually, and many still rely on mail. Now, the IRS deadline depends on processing, not drop-off time. A return mailed on April 15 can still be marked late. That shift increases IRS late filing penalties and interest charges instantly. USPS mail delays and new sorting rules drive this change. Taxpayers must act early, use certified mail, or file electronically. Understanding USPS postmark rules 2026 is now essential to avoid costly IRS penalties.