Earnouts were designed to solve a specific problem: the valuation gap between what a seller believes their business is worth today and what a buyer is willing to pay. When a target company projects strong forward revenue growth, or a product is mid-cycle through a regulatory pathway, the parties often cannot agree on a present-value number. The earnout defers a portion of the purchase price, tying it to post-closing performance. The commercial logic holds. The drafting, in many transactions, does not.
Earnout disputes are a distinctly post-closing phenomenon. They rarely arise because the parties disagreed about the commercial outcome they wanted. They arise because the language used to describe the calculation was written under deal-fatigue conditions, by professionals who assumed both sides shared the same mental model of what "EBITDA" or "revenue" or "product launch" meant. They do not always share that model, and the document does not always resolve the difference.
Why Earnout Provisions Get Drafted Last
By the time earnout mechanics reach the drafting stage, the principal economic terms are agreed, both parties are ready to close, and the attention that the clause demands gets traded for speed. The result is placeholder language: "EBITDA as calculated consistent with past practice," or "revenue recognized in accordance with GAAP," or "upon commercial launch of the product." Each phrase sounds workable until the buyer and seller are six months post-closing, running separate spreadsheets with different results.
EBITDA is the most common source of post-closing calculation disputes in earnout provisions. A definition that does not specify the treatment of acquisition-related amortization, integration costs allocated from the parent, management fee charges, changes in depreciation schedules, or modifications to capitalization policy creates room for legitimate disagreement. The buyer may load the acquired business with overhead that did not exist pre-closing, each item defensible under the terms of the agreement as written. The seller calculates the metric using pre-closing methodology. Both may be technically consistent with the definition.
Revenue Definitions and Milestone Ambiguity
Revenue-based earnouts require the same definitional discipline. A target metric expressed as "product revenue" without specifying whether that includes services, maintenance, or professional fees tied to the product; whether it covers revenue recognized in the period or billed in the period; whether geographic scope limitations apply; and how renewals and upgrades are treated, is not a revenue definition. It is a starting point for a dispute.
Milestone-based earnouts introduce a different problem. Where the trigger is a qualitative or operational event, such as product launch, regulatory clearance, customer count, or market entry, the ambiguity is harder to resolve with arithmetic. If an earnout triggers upon the product being "commercially available" in a named market, and the buyer and seller disagree on whether a limited early-access release satisfies that definition, there is no reconciliation process that resolves it. A court or arbitrator must decide which interpretation was intended at signing, based on sparse contractual language.
The drafting remedy is specificity. Milestone definitions should identify objectively verifiable conditions: first revenue from a specified class of paying customers, listing on a named distributor platform, receipt of a named regulatory designation, or a stated number of active users as tracked by a defined system. Language that leaves "launch" open to interpretation typically reflects a failure to have the difficult conversation about what launch actually means before closing, not an intentional decision to leave it flexible.
Post-Closing Conduct Obligations
The earnout structure creates a governance problem that standard deal documentation is not built to handle: the buyer operates the business post-closing, but the seller retains an economic stake in how it is operated for the next two or three years. Most agreements address this through a buyer conduct covenant, a general promise to operate the acquired business in the ordinary course without taking actions designed to reduce earnout payments.
These covenants are frequently insufficient. "Ordinary course" has a pre-closing reference point that becomes increasingly meaningless as integration proceeds. A buyer may legitimately redirect the acquired business's sales resources toward higher-margin product lines, modify the pricing structure, shift revenue attribution between business units, or eliminate a particular sales territory, all without violating a general conduct covenant and all while materially affecting whether the earnout threshold is reached.
The more durable approach is specific. Seller counsel should identify the operational decisions most likely to affect the earnout metric and negotiate explicit consent rights or notice requirements for those categories: changes to the pricing structure of the acquired product, reallocation of dedicated sales or product personnel, changes to the product roadmap that would reasonably affect target revenue, and the method by which integration costs are allocated from the parent entity. A general conduct covenant backed by specific enumerated protections is materially stronger than one standing alone.
Accounting Methodology Disputes
Post-closing changes in accounting methodology generate a category of earnout disputes that practitioners sometimes overlook at the drafting stage. When a buyer integrates the acquired business into its financial reporting structure, it may harmonize revenue recognition policies, depreciation schedules, or cost allocation methods across the combined entity. These are legitimate business and accounting decisions. They can also change the earnout calculation in ways neither party anticipated.
If the buyer adopts a revenue recognition policy for the acquired business that differs from the seller's pre-closing approach, both sides can produce defensible numbers using different inputs. The fix is direct: specify which accounting policies govern the earnout calculation, state that any policy change requires mutual written consent before taking effect in the earnout period, and include a fallback calculation methodology if the parties cannot agree. A determination by a named class of neutral accounting expert, with a defined engagement and fee process, should be specified for disputes that survive the initial reconciliation window.
Dispute Resolution Mechanics
The dispute resolution provision for earnout calculations deserves more attention than it typically receives. General commercial arbitration, while appropriate for legal interpretation disputes, is an inefficient vehicle for disagreements that are primarily mathematical. An expert determination by a specified accounting firm, with a defined scope limited to the calculation mechanics in dispute, is faster and typically more technically accurate.
The timing mechanics also matter. The agreement should specify the window within which the buyer must deliver the earnout calculation, the period within which the seller may object and provide a counter-calculation with supporting documentation, and the process for engaging the neutral if the parties cannot resolve the difference. Any timeline that is left undefined creates negotiating power for the party with a stronger post-closing position, who can delay the process through ambiguity rather than merit.
We are not suggesting earnouts should be avoided. They genuinely solve valuation problems that cannot be resolved through price alone. The issue is that earnout provisions require the same definitional precision as the representations section, and in most deals, they do not receive comparable attention. A reviewer who clears the earnout metrics quickly because the headline number looks reasonable will miss the places where the dispute actually lives: in the calculation definition, in the treatment of integration costs, and in the absence of specific conduct protections for the period when the seller's equity is at stake but the buyer holds operational control.