What Is Withdrawal Liability in Multiemployer Pension Plans?

Withdrawal liability in multiemployer pension plans is the debt an employer owes when it leaves a union-sponsored pension plan that covers multiple employers. It equals the employer’s share of the plan’s unfunded vested benefits, meaning the gap between the pensions the plan has promised and the assets it has to pay them. Congress created this obligation in the Multiemployer Pension Plan Amendments Act of 1980 to keep departing employers from pushing their pension costs onto the ones that stay.¹ Assessments routinely run into the six and seven figures, and the deadlines for contesting them are short and unforgiving.

What Counts as a Withdrawal

Liability is triggered by one of two events: a complete withdrawal or a partial withdrawal.

A complete withdrawal happens when an employer permanently stops contributing to the plan or permanently shuts down all operations covered by it.² The common paths there are closing a unionized operation, letting a collective bargaining agreement expire without renewal, or selling the business without meeting the asset-sale rules described below.

A partial withdrawal happens when participation drops sharply but does not end. Federal law recognizes two forms.³ The 70-percent decline test looks at a three-year testing period: in each year, the employer’s contribution base units must fall below 30 percent of the average of the two highest years in the five years before the testing period. The partial cessation trigger applies when an employer stops contributing under one or more collective bargaining agreements but keeps performing the same type of work in the plan’s jurisdiction.

Restructuring around these rules is risky. If a principal purpose of a transaction is to evade or avoid withdrawal liability, the statute instructs that liability be determined as if the transaction had not occurred.⁴ Plan sponsors and the PBGC look hard at timing when corporate reorganizations, asset transfers, or workforce reductions precede a withdrawal.

How the Bill Is Calculated

The number depends on which allocation method the plan uses. Federal law supplies a default and permits alternatives.

Under the default presumptive method, the plan’s unfunded vested benefits are divided into annual layers. For each layer, the employer’s share is a fraction: its required contributions for that year and the four preceding years, divided by all employers’ contributions over the same five-year window.⁵ Each layer is amortized, and the unamortized amounts are summed. Plans can also adopt a modified presumptive method, a rolling-five method, or a direct attribution method that traces unfunded benefits to specific employees.

Timing drives everything. An employer that contributed steadily for decades and then withdrew while the plan was deeply underfunded will owe far more than one that participated briefly when the plan was healthy, even on identical contribution histories.

Who Is on the Hook

Liability does not stop at the entity that signed the collective bargaining agreement. Under ERISA, all trades or businesses under common control are treated as a single employer for withdrawal liability purposes, using the same framework the IRS applies under Section 414(c) of the Internal Revenue Code.⁶

In practice, a sole proprietor is personally liable for the business’s withdrawal debt. Partners are each on the hook. A parent corporation that controls several subsidiaries can find every subsidiary jointly and severally liable even when only one subsidiary ever contributed to the plan. Private equity funds holding controlling interests in portfolio companies have been pulled into controlled-group liability as well. This is where the obligation blindsides owners. Any ownership-changing transaction involving a company that participates in a multiemployer plan deserves a controlled-group analysis before closing, not after.

After the Demand Letter

Once the plan sponsor finishes its calculation, it sends the employer a notice and demand that states the total liability and the payment schedule.⁷ From that moment, three clocks start.

The 90-Day Review Window

The employer has 90 days to ask the plan sponsor to review specific aspects of the determination, identify inaccuracies in the unfunded vested benefits calculation, or submit additional relevant information.⁷ A review request has to point to specific errors, not just register disagreement. Common challenges include the withdrawal date, the actuarial assumptions used to value the plan’s liabilities, and whether the plan applied the right allocation method. An employer that lets the 90 days pass can lose the ability to raise certain defenses in arbitration later.

The 60-Day Pay-Now Rule

Payments must begin no later than 60 days after the demand, whether or not the employer is contesting the assessment.⁷ Courts call this the “pay now, dispute later” rule.⁸

Each annual payment equals the average of the employer’s three highest years of contribution base units out of the ten years before withdrawal, multiplied by the employer’s highest contribution rate during that same ten-year period.⁷ Payments continue until the liability is amortized, capped at 20 annual installments if full amortization would otherwise take longer. Installments are usually quarterly, though plans can set a different period.⁹

Arbitration

Disputes over the plan sponsor’s determination go to arbitration, not court. Either side can start arbitration within 60 days after the earlier of two dates: when the plan sponsor responds to the review request, or 120 days after the request was made.¹⁰ The parties can also jointly initiate arbitration within 180 days after the original demand. The plan is not required to respond to the review request at all, so an employer waiting for an answer can easily blow the deadline.

The burden sits with the employer. The plan sponsor’s determination is presumed correct, and the employer must show by a preponderance of the evidence that it was unreasonable or clearly erroneous.¹⁰ A challenge to actuarial methods requires proving the assumptions were, in the aggregate, unreasonable given the plan’s experience, or that the actuary made a significant error in applying them. Most employers cannot overturn a determination without a plain factual mistake in the contribution records or a clear misapplication of the allocation formula. If no one initiates arbitration in time, the amounts demanded become due on the plan’s schedule, and the plan can sue to collect. After an award, either party has 30 days to bring a federal court action to enforce, vacate, or modify it.

Default and Acceleration

A default occurs when an employer misses a payment and does not cure within 60 days after written notice from the plan sponsor.⁷ A plan’s own rules can add other default triggers, including events suggesting the employer is unlikely to be able to pay.

Once a default is declared and not cured, the plan sponsor can accelerate the entire outstanding balance and demand immediate payment, with interest running from the first missed payment’s due date.⁷ The PBGC sets the interest rate on overdue payments quarterly, based on the average quoted prime rate for short-term commercial loans reported by the Federal Reserve.¹¹ For the first two quarters of 2026, the rate is 6.75 percent.¹² A plan may adopt its own rate under separate PBGC regulations, so the actual rate charged can differ.

Ways to Reduce or Avoid the Liability

The Asset-Sale Cap

An employer that sells all or substantially all of its assets at arm’s length to an unrelated buyer gets a statutory cap on its withdrawal liability. The cap is a sliding scale tied to the employer’s post-sale liquidation value, meaning assets minus all liabilities other than the withdrawal liability itself.¹³ At the low end, liability is capped at 30 percent of liquidation value up to $5 million; at the high end, for liquidation value over $25 million, the cap is $10.875 million plus 80 percent of the amount above $25 million, with graduated bands in between. The cap applies only to genuine sales to unrelated buyers and does not help employers in bankruptcy reorganization.

The Asset-Sale Exception

A separate provision lets an employer sell its business without triggering withdrawal liability at all, if three conditions are met.¹⁴ First, the buyer must assume the obligation to contribute to the plan for substantially the same number of contribution base units as the seller. Second, the buyer must post a bond or escrow equal to the greater of the seller’s average annual contribution over the three preceding plan years or its contribution for the last plan year before the sale, kept in place for five plan years and paid to the plan if the buyer withdraws or misses a contribution. Third, the sale contract must provide that if the buyer withdraws within those five years, the seller is secondarily liable for what it would have owed without the exception.

All three conditions have to be satisfied. Miss one and the seller faces a withdrawal the moment it stops contributing. Buyers often resist the bonding or contribution-continuity terms, which can either kill the deal or force the seller to accept a lower price to account for the exposure.

The Free-Look Rule

Employers that first joined a multiemployer plan after September 26, 1980, can qualify for a full exemption if the plan has adopted the free-look rule. The employer must have contributed for no more than the lesser of six consecutive plan years or the plan’s vesting period, with contributions in each year under 2 percent of all employer contributions, and must not have used the rule to avoid liability from the same plan before.¹⁵ The plan must have amended its rules to offer the free look, and its ratio of assets to benefit payments in the year before the employer joined must have been at least eight to one. Not every plan adopts this provision, and underfunded plans cannot meet the asset ratio. New entrants should confirm availability before assuming they can exit cleanly.

Industry-Specific Rules

Some industries get modified triggers because of how work is structured in the field. In building and construction, a complete withdrawal does not occur merely because an employer stops contributing; it occurs only if the employer stops contributing and then continues to perform the same type of covered work in the same jurisdiction, or resumes that work within five years without renewing contributions.² The look-back shrinks from five years to three if a mass withdrawal has terminated the plan. The entertainment industry gets a parallel carve-out for temporary and project-based work in theater, motion picture, radio, television, music, and dance. Separate statutory rules govern the trucking, household goods moving, and public warehousing industries, with their own definitions of withdrawal and allocation and payment mechanics.⁹

Mass Withdrawal

If every employer withdraws from a plan, or all employers end their obligation to contribute, the plan terminates by mass withdrawal.¹⁶ For an individual employer caught up in one, the practical point is that payment obligations to the terminated plan end when the PBGC determines plan assets are sufficient to meet all obligations.¹⁷ Mass withdrawals tend to arise in declining industries, where the remaining employer base is too small to sustain the plan and the resulting assessments are both the largest and the hardest to negotiate.

1
Pension Benefit Guaranty Corporation. Introduction to Multiemployer Plans
2
Office of the Law Revision Counsel. 29 USC 1383 – Complete Withdrawal
3
Office of the Law Revision Counsel. 29 USC 1385 – Partial Withdrawals
4
Office of the Law Revision Counsel. 29 USC 1392 – Obligation to Contribute
5
Office of the Law Revision Counsel. 29 USC 1391 – Methods for Computing Withdrawal Liability
6
Office of the Law Revision Counsel. 29 USC 1301 – Definitions
7
Office of the Law Revision Counsel. 29 USC 1399 – Notice, Collection, Etc., of Withdrawal Liability
8
United States District Court for the Middle District of Pennsylvania. Miller v. Lehigh Coal and Navigation Company
9
Pension Benefit Guaranty Corporation. Withdrawal Liability
10
Office of the Law Revision Counsel. 29 USC 1401 – Resolution of Disputes
11
eCFR. 29 CFR 4219.32 – Interest on Overdue, Defaulted and Overpaid Withdrawal Liability
12
Pension Benefit Guaranty Corporation. Late or Defaulted Withdrawal Liability
13
Office of the Law Revision Counsel. 29 USC 1405 – Limitation on Withdrawal Liability
14
Office of the Law Revision Counsel. 29 USC 1384 – Sale of Assets
15
Office of the Law Revision Counsel. 29 USC 1390 – Nonapplicability of Withdrawal Liability for Certain Temporary Contribution Obligation Periods
16
Office of the Law Revision Counsel. 29 USC 1341a – Termination of Multiemployer Plans
17
Pension Benefit Guaranty Corporation. General Duties of a Plan Sponsor of a Terminated Multiemployer Plan