Collective Bargaining Agreements in M&A: What Sellers With a Unionized Workforce Need to Know

Selling a business with a unionized workforce introduces a set of obligations, timelines, and liabilities that do not exist in non-union transactions. Most M&A guidance — including the majority of what founders read — assumes a non-union workforce. Sellers with CBAs who enter a process with a non-union framework will encounter unexpected complexity in four specific areas: the CBA's change-of-control provisions, the successor employer doctrine under the NLRA, multi-employer pension plan withdrawal liability, and WARN Act obligations.

None of these issues is necessarily deal-preventing. Transactions involving unionized workforces close regularly. What matters is whether the seller identifies and documents these obligations before a process begins — on their timeline, with their advisors constructing the narrative — or whether buyers discover them in diligence, price the uncertainty, and introduce structural protections the seller did not anticipate.

What the CBA actually says about a sale

Every CBA is different. There is no standard change-of-control provision, and the specific language in the seller's agreement determines what obligations arise at the transaction level. The analysis begins with reading the CBA — the entire document, not just the section labeled "successors and assigns."

Change-of-control provisions in CBAs typically fall into one of four categories. The first category requires the seller to provide advance notice to the union before signing a transaction agreement. The specific timeline varies: 30, 60, or 90 days is common. Failure to provide required notice gives the union a grievance claim that can delay closing.

The second category requires the buyer to assume the CBA as a condition of closing. These provisions are most common in asset purchase transactions and are among the most significant terms a buyer will negotiate. A buyer who must assume a CBA with above-market wage rates, rigid work rules, or unfavorable benefit cost structures will price that assumption into the purchase price.

The third category gives the union renegotiation rights triggered by the transaction. These provisions require the parties to meet and bargain over specified terms within a defined period after close. They do not necessarily require the buyer to accept any particular terms, but they create an obligation to bargain in good faith and can extend post-close uncertainty.

The fourth category is silence — the CBA has no explicit change-of-control provision. Silence does not mean the buyer has no obligations. It means the analysis shifts to the NLRA successor employer doctrine.

The successor employer doctrine: what buyers inherit

The National Labor Relations Act's successor employer doctrine creates obligations for buyers even when the CBA itself is silent on the transaction. Under NLRB and federal court precedent, a buyer who acquires substantially all of a unionized business's assets and continues operating the same business with a majority of the seller's bargaining unit employees is a "successor employer" — and is required to recognize and bargain with the union before changing wages or terms of employment.

The successor employer doctrine applies independently of whether the transaction is structured as a stock sale or an asset sale. In a stock sale, the buyer steps into the seller's shoes as the employer — the existing CBA typically continues in force automatically. In an asset sale, the buyer may argue it is a "new" employer, but if the successor employer criteria are met, the bargaining obligation attaches regardless of deal structure.

Successor employer status does not require the buyer to assume the existing CBA verbatim. It requires the buyer to recognize the union as the bargaining representative and to bargain in good faith before implementing changes to wages and working conditions. In practice, most buyers negotiate the terms of a new or amended agreement during the diligence and SPA negotiation period, so that the post-close labor arrangement is defined before closing.

Sellers should provide buyers with complete information about the existing CBA, the composition of the bargaining unit, current wage rates versus market rates, pending grievances, and the history of prior negotiations. Buyers who receive this information early in the process can model the successor employer scenario and include the bargaining outcome in their investment thesis rather than treating it as a post-close uncertainty.

Multi-employer pension plans: the largest hidden liability

Multi-employer pension plans — collectively bargained defined benefit plans covering employees across multiple employers in the same industry — are among the most significant and least understood liabilities in transactions involving unionized workforces.

When a company withdraws from a multi-employer pension plan — which can be triggered by an asset sale that results in the buyer not continuing to contribute to the same plan — the withdrawing employer becomes liable for its proportionate share of the plan's unfunded vested benefits. This is called withdrawal liability.

Withdrawal liability is triggered by an asset sale when the buyer does not continue contributing to the same multi-employer plan. Stock sales do not trigger withdrawal unless there is an operational change that constitutes a "partial withdrawal." This distinction — asset sale as withdrawal trigger, stock sale as potentially not — is one of the reasons that deal structure decisions in unionized transactions require labor and benefits counsel involved specifically in the pension analysis.

The pre-process action is to obtain a withdrawal liability estimate from the plan's actuary or the plan administrator before launching the process. Most multi-employer plans will provide a withdrawal liability estimate on request. That estimate, combined with a deal structure analysis from benefits counsel, tells the seller whether withdrawal liability is a transaction cost that must be disclosed and addressed in the purchase price negotiation — or whether deal structure can reduce or eliminate the exposure.

WARN Act obligations in transactions with workforce changes

The Worker Adjustment and Retraining Notification Act requires employers to provide 60 days' advance notice of plant closings or mass layoffs affecting 50 or more employees. WARN obligations arise independently of any CBA — they apply to all employers with 100 or more employees, unionized or not.

In M&A transactions, WARN obligations become relevant when the transaction involves, or is expected to lead to, material workforce reductions. The most common WARN scenarios in LMM transactions are: a buyer who plans to consolidate facilities post-close; a seller who is closing an operation as part of the pre-close separation; or a transaction structure that involves the sale of some operations and the wind-down of others.

The WARN analysis must be completed before the LOI is signed, not after. Buyers who have not modeled WARN exposure from their intended post-close restructuring may discover the liability during SPA negotiation, at which point they will seek an indemnification provision or purchase price adjustment. Sellers who complete the WARN analysis themselves, and structure the disclosure accordingly, retain more control over how the liability is allocated.

Many CBAs include WARN notice provisions that go beyond the federal baseline — some require 90 or 120 days' notice, some apply to smaller workforce reductions than the federal threshold, and some include union notification requirements that are separate from employee notice. The CBA's notice provisions must be analyzed alongside the federal and applicable state WARN requirements.

Open grievances and their treatment in diligence

Grievances are formal disputes filed by the union or individual employees under the grievance and arbitration procedures of the CBA. Open grievances at the time of a transaction are disclosed on the representations and warranties schedule and become a specific buyer diligence focus.

Most open grievances in LMM businesses are routine — disciplinary disputes, scheduling disagreements, benefit interpretation questions — and resolve without material liability. But buyers evaluate the aggregate pattern of grievances as a signal of labor relations quality, and specific categories of unresolved grievances can create material liability.

The pre-process labor diligence package that addresses open grievances most effectively includes a complete grievance log for the prior 36 months with status, estimated liability, and resolution history; a description of the grievance process and typical resolution timeline; and, for any grievance with potential liability above the materiality threshold, a legal assessment of the seller's exposure.