Individual Tax Calendar: Key Deadlines for the Remainder of 2026
By Mahoney
Yes, the April 15 tax deadline is now behind us. But there are also deadlines during the rest of the year that are important to be aware of. To help you not miss any, here’s when some key tax-related forms, payments, and other actions are due. Keep in mind that this list isn’t all-inclusive. There may be additional deadlines that apply to you.
Please review the calendar and let us know if you have any questions about the deadlines or would like assistance in meeting them.
June 15
- File a 2025 individual income tax return (Form 1040 or Form 1040-SR) or file for a four-month extension (Form 4868) if you live outside the United States and Puerto Rico or you service in the military outside those two locations. Pay any tax, interest, and penalties due.
- Pay the second installment of 2026 estimated taxes (Form 1040-ES) if not paying income tax through withholding or not paying sufficient income tax through withholding.
September 15
- Pay the third installment of 2026 estimated taxes (Form 1040-ES) if not paying income tax through withholding or not paying sufficient income tax through withholding.
September 30
- If you’re the trustee of a trust of the executor of an estate, file an income tax return for the 2025 calendar year (Form 1041) if an automatic five-and-a-half-month extension was filed. Pay any tax, interest, and penalties due.
October 15
- File a 2025 individual tax return (Form 1040 or Form 1040-SR) if an automatic six-month extension was filed (or if an automatic four-month extension was filed by a taxpayer living outside the United States and Puerto Rico or serving in the military outside those two locations). Pay any tax, interest, and penalties due.
- Make contributions for 2025 to certain retirement plans or establish a SEP for 2025 if an automatic six-month extension was filed.
- File a 2025 gift tax return (Form 709) if an automatic six-month extension was filed. Pay any tax, interest, and penalties due.
December 31
- Make your 2026 contributions to certain employer-sponsored retirement plans.
- Make 2026 annual exclusion gifts (up to $19,000 per recipient).
- Incur various expenses that potentially can be claimed as itemized deductions on your 2026 tax return. Examples include charitable donations, medical expenses, and property tax payments.
©2026
For more details on individual tax extensions this year, read this related blog by Tyler, Sauve, CPA, Manager on our Tax & Business Solutions Team.
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