2026 Tax Deadline Calendar

Fourth quarter estimated tax payment for the 2025 tax year. Applies to individuals with self-employment income, investment income, or other earnings not subject to withholding, as well as corporations making estimated payments.

Employers must furnish W-2 forms to employees and file copies with the SSA. Businesses must also issue 1099-NEC forms to independent contractors and file with the IRS. Late filings may result in penalties.

Form 1120-S (S-Corps) and Form 1065 (Partnerships) are due. These are pass-through entities, so K-1 schedules must also be issued to shareholders and partners by this date. File Form 7004 to request a 6-month extension.

Form 2553 must be filed by March 15 for the S-Corp election to be effective for the current tax year. Missing this deadline means waiting until next year unless relief provisions apply.

Form 1040 is due for the 2025 tax year. This is also the deadline to file for a 6-month automatic extension using Form 4868. Remember: an extension to file is not an extension to pay — any taxes owed are still due April 15.

First quarter estimated tax payment for the 2026 tax year. Individuals and businesses with expected tax liability should make quarterly payments using Form 1040-ES (individuals) or Form 1120-W (corporations).

Form 1120 is due for calendar-year C-Corporations. File Form 7004 to request a 6-month automatic extension to October 15. Any tax owed must still be paid by the original April 15 deadline.

Tax-exempt organizations with a calendar year-end must file Form 990, 990-EZ, or 990-N by this date. An automatic 6-month extension is available by filing Form 8868. Failure to file for three consecutive years results in automatic loss of exempt status.

Second quarter estimated tax payment for the 2026 tax year. Also the deadline for U.S. citizens and resident aliens living abroad to file their 2025 individual income tax return (automatic 2-month extension from April 15).

Third quarter estimated tax payment for the 2026 tax year. If you've had changes in income — a large sale, new clients, or investment gains — this is a good time to recalculate your quarterly estimate to avoid penalties.

If a 6-month extension was filed, Form 1120-S (S-Corps) and Form 1065 (Partnerships) are now due. Updated K-1 schedules must be issued to shareholders and partners to complete their individual returns before October 15.

Deadline for individuals who filed a 6-month extension (Form 4868). Form 1040 must be filed by this date. This is also the extended deadline for C-Corporation returns (Form 1120) that requested an extension.

Tax-exempt organizations that filed Form 8868 for a 6-month extension must submit their Form 990, 990-EZ, or 990-N by this date. Ensure all schedules, including Schedule O, are complete and accurate.

Fourth quarter estimated tax payment for corporations. Note: for individuals, the Q4 estimated payment is due January 15, 2027. This is the last quarterly payment deadline of the corporate tax year.

Last day to take actions that affect your 2026 tax liability: make charitable contributions, harvest investment losses, maximize retirement contributions, purchase business equipment (Section 179), and finalize entity restructuring decisions.