Plan sponsors of single-employer defined benefit plans can ask the IRS for permission to use their own mortality tables instead of the standard mortality assumptions, as long as they have enough reliable data to support it.

Starting with plan years that begin on or after January 1, 2026, sponsors who were previously approved to use custom tables (before January 1, 2025) will need to reapply if their plan’s covered population has changed significantly, by more than 20%. This applies even if only the male or female portion of the population changed, not necessarily the total.

This reapplication process could be especially challenging for plans that use combined-gender mortality ratios, since even a shift in one gender group could trigger the requirement.

If a sponsor doesn’t reapply, they’ll have to go back to using the IRS’s standard mortality assumptions starting in 2026.

Simplified Reapproval Requirements for Custom Mortality Tables

The IRS has released updated guidance (Revenue Procedure 2025-21) that simplifies the rules for certain retirement plans needing to reapply for approval of their custom mortality tables—tables used to estimate how long plan participants are expected to live.

The key change is a more flexible approach to determining when a new application is needed. If your plan’s participant population hasn't changed much since your tables were first approved, you might not need to go through the approval process again in 2026.

Specifically, reapproval won't be required if:

• Your plan uses a combined-gender mortality ratio (a single mortality estimate applied to both men and women, as allowed by IRS regulations), and
• The number of people covered by your plan this year is between 80% and 120% of the average number covered when your tables were first created.

This change is intended to reduce unnecessary paperwork and provide relief to plan sponsors whose participant base has stayed relatively stable.

What Should Plan Sponsors Be Doing Now

Plan sponsors should take the following steps now to determine whether they qualify for this relief:

1. Confirm how your substitute mortality tables were developed. This relief pertains to plans with a single combined-gender mortality ratio.
2. Compare current covered headcount (male + female) to the average during your experience study period. Plans within the 80% to 120% band may avoid reapproval.
3. Engage your actuary. They can determine whether a written certification can be made regarding the continued predictive accuracy of the tables.
4. Plan ahead. If your plan’s population has changed significantly or doesn’t meet the 80% to 120% threshold, you’ll need to begin preparing a new submission to the IRS or use the IRS’s standard mortality assumption.

By taking proactive steps now, plan sponsors can avoid unnecessary filings and streamline compliance as the 2026 mortality table updates take effect.