How Earn-Outs Work in M&A: A Practical Guide for Sellers and Buyers

Earn-outs are one of the most powerful — and most misunderstood — deal structures in mergers and acquisitions. When structured well, they bridge valuation gaps and align the interests of buyer and seller. When structured poorly, they become a source of conflict, litigation, and regret. For anyone involved in a UK business sale, understanding earn-outs is essential.

This guide provides a thorough, practical explanation of how earn-outs work, how to negotiate them effectively, where the risks lie, and how UK tax treatment affects your net proceeds. Whether you're considering selling your business or acquiring one, this knowledge will serve you well at the negotiating table.

What Is an Earn-Out?

An earn-out is a contractual provision in a business sale where a portion of the purchase price is deferred and made contingent on the business achieving specified performance targets after completion. In essence, the seller agrees to accept less cash upfront in exchange for the opportunity to receive additional payments if the business performs well under new ownership.

A typical earn-out might structure a £10 million deal as £7 million paid at completion plus up to £3 million payable over two years if the business achieves specified EBITDA targets. The seller receives guaranteed consideration of £7 million, with the potential to receive up to £10 million if targets are met.

Why Earn-Outs Exist in M&A

Earn-outs exist primarily to bridge valuation gaps between buyer and seller. The seller believes the business is worth £10 million based on its growth trajectory. The buyer, applying a more conservative assessment of risk, values it at £7 million. An earn-out allows both parties to proceed: the seller has the opportunity to achieve their target price, and the buyer limits their downside risk by linking part of the consideration to proven performance.

Earn-outs are particularly common in situations where the business is heavily dependent on the selling owner (with the earn-out incentivising continued involvement), where future performance is uncertain (such as businesses with new products, untested markets, or pending contracts), and where the seller's financial projections are significantly more optimistic than the buyer's assessment.

In the UK mid-market, earn-outs feature in approximately 25-35% of transactions. Their prevalence has increased in recent years as buyers have become more cautious about paying premium prices based on forward-looking projections. Understanding how to negotiate and structure earn-outs effectively has become an essential skill for both sellers and their advisers.

Earn-Out Mechanics Explained

The mechanics of an earn-out — how targets are defined, measured, and paid — determine whether the arrangement works fairly for both parties or becomes a source of conflict.

Choosing the Right Financial Metric

The most commonly used earn-out metrics in UK transactions are EBITDA, revenue, and gross profit. Each has advantages and disadvantages that affect both parties differently.

EBITDA is the most popular metric because it measures underlying profitability and is the standard valuation measure. However, EBITDA can be influenced by the buyer's post-acquisition decisions — for example, by allocating head office costs to the acquired business, changing accounting policies, or making investments that depress short-term earnings. These risks need to be addressed through carefully drafted protective provisions.

Revenue is simpler and harder for the buyer to manipulate, making it attractive to sellers. However, revenue-based earn-outs can incentivise unprofitable growth (the seller books revenue at any cost to hit targets) and don't reward the profitability improvements that create genuine value.

Gross profit offers a middle ground — harder to manipulate than EBITDA but more meaningful than revenue. It's particularly suitable for businesses where the seller's primary contribution is commercial (winning and retaining customers) rather than operational. For more on these financial metrics, see our comprehensive EBITDA guide.

Setting the Earn-Out Period

Earn-out periods in UK transactions typically range from one to three years. Shorter periods favour sellers (less time for buyer interference and quicker payment), while longer periods favour buyers (more time to assess sustainable performance and spread risk).

The appropriate period depends on the nature of the business. A services business with annual contract renewals might suit a two-year earn-out aligned with contract cycles. A technology business launching a new product might need a three-year period to capture the product's market traction. As a general principle, the earn-out period should be the minimum required to credibly demonstrate that performance targets have been genuinely achieved.

Caps, Thresholds, and Accelerators

Well-structured earn-outs include several key provisions beyond the basic target. A threshold sets the minimum performance level below which no earn-out is payable. A cap sets the maximum total earn-out payment, protecting the buyer from unlimited exposure. Accelerators provide enhanced payments for exceeding targets, rewarding exceptional performance.

For example, an earn-out might specify: no payment if EBITDA falls below £1 million (the threshold), a payment of 50% of EBITDA between £1 million and £1.5 million (the standard rate), a payment of 75% of EBITDA above £1.5 million (the accelerator), subject to a maximum total earn-out of £3 million (the cap).

Earn-Out Negotiation Strategies

Earn-out negotiation is where the real value is created or destroyed. Both parties need to approach these discussions with clarity about their objectives and a thorough understanding of the mechanics.

Negotiation Tips for Sellers

As a seller, your priority is to maximise the guaranteed consideration (the upfront payment) and ensure that earn-out targets are achievable and within your control. Key negotiation points include: maximising the upfront payment as a proportion of the total deal value (aim for at least 60-70%), insisting on targets based on metrics you can directly influence, securing protective provisions that prevent the buyer from artificially suppressing performance, retaining operational autonomy during the earn-out period, and ensuring clear, objective measurement criteria that leave no room for interpretation.

Perhaps most importantly, insist on a detailed "earn-out operating framework" that specifies how the business will be run during the earn-out period. This should cover budgets, capex approvals, headcount decisions, pricing policies, and any other factors that could affect the earn-out metrics. Without this framework, you're at the mercy of the buyer's decisions.

Negotiation Tips for Buyers

As a buyer, your priority is to ensure that earn-out payments genuinely reflect incremental value created. Key negotiation points include: setting targets that represent genuine outperformance rather than business-as-usual, retaining sufficient operational control to integrate the business effectively, ensuring targets account for any synergies or cost savings you plan to implement, and including provisions for adjusting targets if extraordinary events occur.

Buyers should also consider the practical implications of having a seller who remains involved during the earn-out period. The seller's incentive is to maximise earn-out metrics, which may not always align with the buyer's broader strategic objectives. Clear governance arrangements and regular communication are essential for managing this tension productively.

Dispute Risks and How to Mitigate Them

Earn-out disputes are among the most common and contentious forms of post-completion conflict in M&A. Research suggests that earn-out provisions are challenged in 30-50% of cases, making robust drafting and clear communication essential.

Common Sources of Earn-Out Disputes

The most frequent sources of disputes include: disagreements over accounting treatment of specific items, buyer actions that the seller claims artificially suppressed performance (such as allocating corporate costs, diverting customers, or reducing investment), ambiguity in target definitions that leads to different interpretations, changes in market conditions or business circumstances that make targets unachievable, and disputes over the calculation of earn-out payments.

Many of these disputes could be avoided with clearer drafting at the outset. The time invested in detailed, precise earn-out provisions during the SPA negotiation is repaid many times over by avoiding costly disputes later.

Protective Provisions to Include

Effective earn-out agreements should include: detailed definitions of all earn-out metrics and how they'll be calculated, a comprehensive list of adjustments that will (and won't) be made to the earn-out metrics, restrictions on buyer actions that could adversely affect earn-out performance, an agreed accounting framework (including policies, procedures, and responsible parties), a dispute resolution mechanism (such as referral to an independent accountant), and information rights allowing the seller to monitor performance during the earn-out period.

Tax Implications of Earn-Outs in the UK

The tax treatment of earn-outs in the UK is complex and can significantly affect the seller's net proceeds. Professional tax advice is essential.

Capital Gains Tax vs Income Tax Treatment

The critical question is whether earn-out payments are treated as capital (subject to capital gains tax, potentially at 10% if Business Asset Disposal Relief applies) or income (subject to income tax at up to 45%). The distinction depends on whether the earn-out is structured as deferred consideration for the sale of shares (capital) or as compensation for the seller's ongoing services (income).

HMRC will examine the substance of the arrangement. If the seller is required to continue working in the business during the earn-out period, and the earn-out payments are linked to their personal contribution, there's a risk that some or all of the earn-out will be treated as employment income rather than capital proceeds.

Careful structuring can mitigate this risk. Key factors include ensuring that earn-out payments are linked to business-wide performance rather than the seller's personal contribution, demonstrating that the seller's continued involvement is not a condition of the earn-out, and structuring the seller's post-completion role and remuneration separately from the earn-out mechanism.

The use of "ascertainable" vs "unascertainable" consideration also affects tax timing. Ascertainable consideration (where the earn-out formula can produce a maximum value) allows CGT to be calculated upfront and adjusted later. Unascertainable consideration may require CGT to be paid on each earn-out payment as it's received.

Earn-Out Trends in the UK Market

The UK earn-out market has evolved significantly in recent years. The proportion of deals including earn-outs has increased from approximately 20% in 2020 to 30-35% in 2026, reflecting greater buyer caution and a more challenging economic environment. The average earn-out period has shortened slightly (from 2.5 years to approximately 2 years), and revenue-based earn-outs have gained popularity relative to EBITDA-based structures.

There's also been a trend towards "hybrid" structures that combine a traditional earn-out with other forms of deferred consideration. For example, a deal might include a fixed deferred payment (providing certainty to the seller) alongside a performance-based earn-out (providing upside potential). These hybrid structures can be attractive to both parties by balancing risk and reward.

Alternatives to Earn-Outs

Earn-outs aren't the only way to bridge valuation gaps. Alternative structures include: vendor loans (where the seller lends part of the purchase price to the buyer, receiving interest and repayment over time), equity rollovers (where the seller retains a minority stake in the business, participating in future value creation), escrow arrangements (where part of the consideration is held in escrow pending the resolution of identified risks), and warranty and indemnity insurance (which transfers specific risks to an insurer rather than managing them through deferred consideration).

Each alternative has different risk, tax, and practical implications. The right structure depends on the specific circumstances of the transaction, the risk profiles of both parties, and the nature of the valuation gap being addressed.

If you're navigating an earn-out negotiation — whether as buyer or seller — professional M&A advice is essential. Our team has extensive experience in structuring and negotiating earn-outs that work for both parties. Book a free strategy call to discuss your specific situation. For buyers, understanding earn-out dynamics is critical for structuring acquisitions that protect your investment whilst maintaining seller motivation.