October 15: Retirement Deadlines Beyond Your Extended Tax Return
For some taxpayers, the date may also matter for 2025 SEP or Solo 401(k) contributions and excess IRA corrections.
October 15 is best known as the federal filing deadline for many people who requested an extension for their 2025 individual income tax return. But, the date can also be important for retirement plan contributions or correcting an IRA overcontribution. The rules depend on the account, business structure and type of contribution, so do not assume every retirement deadline moves to October 15.
SEP IRA Contributions May Have an Extended Deadline
A business generally may make employer contributions to a Simplified Employee Pension (SEP) plan by the due date of its federal income tax return, including extensions. That can give a calendar-year sole proprietor who properly extended a 2025 individual return until October 15, 2026, to make a 2025 SEP contribution. Some corporations may also have an October deadline, depending on their tax year and extension.
A SEP contribution can be made for the business owner and, when required, eligible employees. The contribution must follow the plan’s terms and IRS limits. A self-employed owner’s calculation is different from a standard employee calculation and generally uses net earnings after certain adjustments. If a business has employees, it should check who is eligible and whether contributions must be made for them as well.
The deadline can be earlier for other business structures. For example, a calendar-year S corporation or partnership that extended its 2025 return generally had a September 15, 2026, filing deadline. Confirm the deadline for the business return rather than relying on October 15 as a universal date.
Solo 401(k) Rules Depend on the Contribution
A Solo 401(k), also called an individual 401(k), may allow both employee elective deferrals and employer contributions. Employer contributions, such as profit-sharing contributions, may be made by the employer’s return deadline, including extensions, if the plan and contribution meet the applicable requirements.
Employee deferrals have separate rules. In particular, a sole proprietor setting up a new 401(k) after the end of the tax year must adopt the plan by the unextended tax filing deadline. Special timing rules also apply to first-year elective deferrals. Because an extension does not automatically make every Solo 401(k) action timely, review the plan document and the timing of the deferral election and deposit before making a contribution.
An Extension May Give You Time to Correct an Excess IRA Contribution
If you contributed more than allowed to a traditional or Roth IRA for 2025, the extended due date may give you additional time to correct the excess. In general, withdrawing the excess contribution and related earnings by the return deadline, including a valid extension, can help avoid the 6% excise tax for that year. The tax can apply each year an excess remains in the account.
The tax treatment depends on the facts, including whether the contribution was deducted and when it is withdrawn. Ask the IRA custodian how to process a corrective distribution and have the related earnings calculated. Do not simply request an ordinary withdrawal without confirming that it is being handled as a correction.
A Regular IRA Contribution Deadline Is Different
An extension to file a tax return generally does not extend the deadline to make a regular traditional or Roth IRA contribution for the prior tax year. The deadline for a 2025 IRA contribution was April 15, 2026. October 15 may apply to correcting an excess contribution, but it is not extra time to make an ordinary 2025 IRA contribution.
Check the Details Before the Deadline
Before relying on October 15, identify the tax year, the type of retirement plan, the form of contribution and the business return deadline. Review the plan document, confirm the contribution amount and eligibility, and allow time for the financial institution to process the transaction. Disaster relief can change deadlines for eligible taxpayers, so affected individuals should follow the specific IRS notice that applies to them.
An extension gives more time to file a return, not more time to pay the tax that was due on the original filing date. If you are unsure whether an October 15 retirement-plan deadline applies to you, check with your tax professional before acting.
The article is meant for informational purposes only. Please contact me directly to discuss how this applies to your individual tax situation.