M & K Employee Solutions v. Trustees of the IAM National Pension Fund
In brief
The pension fund's approach to using actuarial assumptions adopted after the measurement date was allowed under federal law.
- Where it stands
- Decided
Decided 9-0 · May 21, 2026 · Opinion by Justice Jackson
- What it’s about
- The Court unanimously ruled for the IAM National Pension Fund, holding that ERISA does not require a pension plan’s actuary to choose the assumptions used to calculate an employer’s withdrawal liability by the measurement date. The Court affirmed the D.C.
- Who it affects
- Multiemployer pension funds may use assumptions adopted after the measurement date when calculating what a withdrawing employer owes.
Summary: written with AI from the case record.
What it's about
Circuit’s decision allowing actuaries to use assumptions adopted after that date.
The case clarifies how multiemployer pension plans can estimate long-term obligations when an employer withdraws.
Question presented
Whether the pension fund correctly calculated the employer's withdrawal liability under the Multiemployer Pension Plan Amendments Act.
What the Court decided
The vote
From the opinions
“ERISA's withdrawal-liability provisions do not require the actuarial assumptions behind the calculation to be selected on or before the measurement date.”
What's next
Lower courts must apply the Court's interpretation in similar withdrawal-liability disputes. Pension funds and withdrawing employers can calculate and challenge liabilities under that rule.
Why it matters
For example, an employer leaving such a plan can face a calculation based on later-adopted predictions about future investment returns and liabilities.
Docket activity
Case data updated: summary, question_presented, generation_metadata
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Opinion added: Opinion of the Court - KJ
Audio Recording added: Oral Arguments - M & K Employee Solutions v. Trustees of the IAM Pension Fund
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More questions
- What did the Supreme Court rule in M & K Employee Solutions?
- The Court said actuarial assumptions for withdrawal liability need not be selected on or before the measurement date. It affirmed the D.C. Circuit.
- Who is affected by the M & K Employee Solutions decision?
- Multiemployer pension funds and employers leaving those plans are affected. Funds may use later-adopted assumptions in calculating an employer's withdrawal liability.
- What happens next after M & K Employee Solutions?
- Lower courts must follow the Court's interpretation in similar cases. Pension funds and employers will apply it when calculating or disputing withdrawal liability.
Sources
Primary materials plus reporting. Best-effort analysis: this explainer relies on a mix of primary materials and trusted secondary sources. Official filings and opinions remain authoritative.