Supreme Court Allows Updated Actuarial Assumptions for Pension Withdrawals

In May 2026, the Supreme Court resolved a circuit split over whether actuaries may use more current assumptions to calculate an employer’s liability when withdrawing from a multiemployer pension plan. Many older adults rely on such plans to help pay for basic housing, food, and health care costs.

Decision: M & K Emp. Sols., LLC v. Trs. of the IAM Nat'l Pension Fund, 146 S. Ct. 1224 (2026)

Holding: In a unanimous, 9-0 decision authored by Justice Ketanji Brown Jackson, the Supreme Court held that a multiemployer pension plan may calculate an employer’s withdrawal liability using actuarial assumptions adopted after the year end measurement date. The Court reasoned that “[r]equiring actuaries to use assumptions selected before the measurement date could therefore prevent them from relying on the most up-to-date data when selecting their assumptions.” M & K Emp. Sols., LLC v. Trs. of IAM Nat’l Pension Fund, 146 S. Ct. 1224, 1229-33 (2026).

AARP and AARP Foundation filed an amicus brief in support of the importance of accurate actuarial assumptions to protect multiemployer pension plan solvency and retirement security.

Implications    

The Supreme Court’s decision supports the long-term stability of multiemployer pension plans by ensuring more accurate calculations of employer withdrawal liability. More importantly, the decision reduces the risk of pension underfunding and helps preserve billions of dollars in pension benefits on which many older adults depend.

Rachel N. Lokken, RLokken@aarp.org