April 15, 2027

April 15, 2027 is the day your 2026 Form 1040 is due, and the day any tax you still owe for 2026 is due. Those are two separate obligations that happen to share a date. You can move the first one six months with Form 4868. You cannot move the second one at all.

What is due

• Form 1040 for the 2026 tax year, or Form 4868 to extend it to October 15, 2027.
• Any 2026 balance you owe, whether or not you extend.
• Your first 2027 estimated payment, if you make them. Same day, separate payment, different tax year.
• Form 1120 for calendar-year C corporations, or Form 7004 to extend it.

If you cannot finish by then

File Form 4868 and pay what you estimate you owe. The estimate does not have to be exact. It has to be a good-faith number, and the closer it is, the less interest you pay. The extension is automatic. The IRS does not ask why and does not reject it for a reason. It rejects it for a typo.

If you cannot pay by then

File anyway. The penalty for not filing is ten times the penalty for not paying. Then look at a payment plan. The failure-to-pay penalty drops by half while an installment agreement is in place, and a plan stops the collection notices from escalating.

The day after

If April 15 passes with no return and no extension, the failure-to-file penalty starts at 5 percent of the unpaid tax for the first month. It reaches 25 percent after five months. File as soon as you can, then use the first-time abatement letter if the last three years were clean.

Common mistake

Filing Form 4868 and treating it as a payment extension. It is not. Interest and the failure-to-pay penalty run from April 15 on whatever you did not pay, extension or no extension.

Sources

1. IRS, About Form 4868
2. IRS, Failure to file penalty
3. IRS, Failure to pay penalty