October 15 Deadline Triggers Year-End Retirement Planning Push for SEP IRAs and Solo 401(k)s

October 15, 2026, is the extended deadline for taxpayers who filed a tax extension to fund SEP IRAs and solo 401(k) plans for the 2025 tax year. Financial advisors say the date also kicks off a critical stretch of year-end retirement planning.

Taxpayers who discovered errors in their 2025 IRA contributions, such as contributing to the wrong type of account or exceeding the $7,000 limit, also have until October 15 to correct those mistakes. The correction can be made by withdrawing the excess contribution and any associated earnings, or by recharacterizing the contribution. This deadline applies regardless of whether the individual has already filed their 2025 return.

Looking ahead to December 31, individuals who turned 73 or older during 2026 must take their required minimum distributions from traditional IRAs and traditional Thrift Savings Plans by year-end. Missing the RMD deadline can trigger significant excise tax penalties.

Financial advisors also recommend completing Roth IRA conversions by mid-December, as some account custodians do not process conversion requests during the final weeks of the year.

December 31 is also the last day for calendar-year taxpayers to sell securities to realize capital gains or losses and to make charitable gifts that qualify for a 2026 tax deduction.

Advisors say October is the right time to review retirement account balances, estimate year-end income, and decide whether a Roth conversion makes sense given current and projected future tax rates.