21 May 2026
M & K Employee Solutions, Inc. v. Trustees of IAM Nat. Pension
- Citation
- M & K Employee Solutions, Inc. v. Trustees of IAM Nat. Pension
- Court
- Supreme Court of the United States
- Case number
- 23-1209
ERISA §§1391 and 1393 do not require actuarial assumptions to be selected on or before the measurement date; the 'as of' language fixes factual inputs as of the measurement date but does not freeze methodological tools, and §1393’s requirement of reasonable, best-estimate assumptions supports permitting actuaries to select assumptions after the measurement date so long as they are reasonable and reflect the actuary’s best estimate.
- Withdrawal liability
- Actuarial assumptions
- Measurement date
- Retroactivity
- Arbitration