SEP-IRA Contribution Deadline (Extended) — October 15
Thursday, October 15, 2026
Final deadline to contribute to a SEP-IRA for 2025 if you extended your return — October 15, 2026.
Who must file or pay
Self-employed individuals and small business owners who extended their 2025 return. SEP-IRA contributions for 2025 can be made up to the extended return deadline.
What you need to know
If you filed Form 4868 to extend your 2025 return, you have until October 15, 2026 to establish and fund a SEP-IRA for the 2025 tax year. This is one of the most powerful last-minute tax planning tools available — you can open a new SEP-IRA and make a large deductible contribution the day before filing your extended return.
The SEP-IRA contribution limit for 2025 is the lesser of 25% of net self-employment income or $70,000. A self-employed professional earning $200,000 in net income can contribute $50,000 to a SEP-IRA and deduct it on their 2025 return.
Solo 401(k) plans, by contrast, must be established by December 31 of the tax year — but contributions can be made through the extended deadline. TaxosAgent compares SEP-IRA vs. Solo 401(k) vs. Defined Benefit plan based on your income and age.
No penalty for missing — you lose the 2025 contribution opportunity. Excess contributions after funding trigger a 6% excise tax.
Required forms
- →Contribution to SEP-IRA custodian (no IRS form)
- →Schedule 1 line 16 on Form 1040
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Other dates to know
Individual Tax Return Deadline — April 15
Federal individual income tax return due April 15, 2026 for tax year 2025.
Individual Extension Deadline — October 15
Final extended deadline to file your 2025 individual federal tax return — October 15, 2026.
C-Corp Extended Deadline — October 15
Final extended deadline for C-Corporation Form 1120 — October 15, 2026.