Purchase Price Adjustment Mechanisms: Locked Box, Completion Accounts, and Earn-Outs

The headline enterprise value is the starting point. The actual equity value paid to the seller is determined by purchase price adjustment mechanisms. These mechanisms allocate economic risk between signing and closing, and they drive some of the most complex negotiations in any deal.

For transaction services teams, the choice of mechanism shapes the diligence scope, the report deliverables, and the post-close workstreams.

Completion Accounts

The most common mechanism in North American transactions. The purchase price is adjusted based on the balance sheet at closing.

How It Works

1. At signing, the parties agree on enterprise value and target levels for net debt, working capital, and sometimes other balance sheet items.
2. At closing, the buyer pays an estimated purchase price based on preliminary estimates.
3. Within 60 to 90 days after closing, the buyer prepares completion accounts measuring actual net debt and working capital at closing.
4. The difference between actual and estimated amounts adjusts the purchase price. Overpayments are refunded. Underpayments are topped up.

Diligence Implications

The transaction services team must deliver:

• A clear net working capital analysis establishing the target working capital level
• A comprehensive net debt bridge identifying all debt-like items
• Accounting policy analysis to establish the basis of preparation for completion accounts
• Sensitivity analysis showing the range of potential adjustments

The diligence team also defines the accounting policies that govern the completion accounts. These policies determine how every balance sheet item is measured at closing. Ambiguous policies create post-close disputes.

Advantages and Risks

For buyers: Protection against balance sheet deterioration between signing and closing. The buyer pays for what it receives at closing.

For sellers: Risk that the buyer will interpret completion accounts aggressively to reduce the final price. The dispute resolution process can extend final settlement by months.

Locked Box

Common in European and auction transactions. The purchase price is fixed based on a historical balance sheet date.

How It Works

1. The parties agree on an equity value based on a reference balance sheet at the locked-box date (typically the most recent audited or interim balance sheet).
2. Between the locked-box date and closing, the seller is prohibited from extracting value from the target (no dividends, management fees, or non-arm's-length transactions). These are called "leakage" provisions.
3. The buyer may compensate the seller for the period between the locked-box date and closing through a daily interest accrual or value uplift.
4. No post-close purchase price adjustment. The price is final at closing.

Diligence Implications

The diligence team must:

• Analyze the locked-box balance sheet in detail, since it determines the final price
• Define and monitor permitted and prohibited leakage categories
• Assess the adequacy of the daily interest or value uplift mechanism
• Review audit trail documentation for all transactions between the locked-box date and closing

The quality of the locked-box balance sheet is critical. Unlike completion accounts, there is no post-close true-up. Any errors in the reference balance sheet flow directly to the buyer.

Advantages and Risks

For sellers: Price certainty. No post-close disputes over balance sheet measurement.

For buyers: Risk that the business deteriorates between the locked-box date and closing. Limited recourse if the locked-box balance sheet contains errors.

Earn-Outs

A portion of the purchase price is contingent on post-close performance. Used when buyer and seller disagree on value or when the seller's continued involvement is critical.

How It Works

1. A portion of the purchase price (typically 10% to 30%) is contingent on the target achieving specified financial or operational milestones after closing.
2. Milestones are typically revenue, EBITDA, or customer metrics measured over one to three years.
3. Payment is made after each measurement period if the milestones are achieved.

Diligence Implications

The transaction services team should:

• Assess the achievability of earn-out targets against historical performance and market conditions
• Review the proposed measurement methodology for manipulation risk
• Analyze the interaction between earn-out metrics and EBITDA adjustments
• Advise on accounting policy provisions that prevent the buyer from undermining earn-out achievement

Earn-out disputes are among the most common sources of post-close litigation. Clear definitions, detailed measurement methodologies, and independent verification reduce this risk.

Advantages and Risks

For sellers: Opportunity to realize full value if the business performs. Bridge the valuation gap.

For buyers: Downside protection if the business underperforms. Alignment of seller incentives during transition.

For both: Earn-outs are complex to negotiate, difficult to administer, and frequently disputed.

Choosing the Right Mechanism

The choice depends on deal dynamics:

Many deals combine mechanisms. A locked-box deal may include a small earn-out for specific growth targets. A completion accounts deal may include an earn-out for retention of key customers.

The Transaction Services Role

Regardless of mechanism, the transaction services team shapes the outcome by defining accounting policies, establishing targets, and producing the analysis that supports price negotiations. Teams that maintain standardized deal workflows across their practice handle these complex mechanisms more efficiently and with fewer errors.