Earn-out in M&A: When It Makes Sense

Macro Consulting Reading: For CEOs, CFOs, COOs, and SME board members in Portugal, this topic should be assessed as a management decision: strategic priority, operational impact, execution risk, and internal capability.

The seller, founder of a B2B software company with €4.2 million EBITDA, had just signed the sale and purchase agreement. She received a significant portion of the agreed value at closing. The remaining significant amount—€3.8 million—was to be paid through a three-year earn-out, contingent on recurring revenue growth per year. Twelve months later, the company was growing, but the buyer changed the commercial policy, increased discounts to gain market share, and reclassified annual contracts as "non-recurring." The earn-out was not triggered. The founder sued. The buyer countersued. Two years of litigation, €340,000 in legal fees, relationship destroyed. The mechanism designed to align interests became the main source of conflict. This is not an isolated case: Harvard Business Review studies indicate that most earn-outs end in dispute or partial payment, and only a minority are fully paid according to initial terms.

The earn-out in M&A is the most widely used deferred payment mechanism in mid-market transactions—and simultaneously the most misunderstood. It allows the buyer to reduce initial risk, the seller to capture future value, and both to share post-acquisition execution risk. But its effectiveness depends on rigorous technical design, unambiguous metrics, and protective clauses that anticipate opportunistic behavior. In Portugal, where a significant share of SME transactions involve some form of deferred payment (APCRI 2023 data), lack of rigor in earn-out structuring is the second leading cause of post-acquisition litigation, only behind warranties and indemnities.

Executive Summary: What Is an Earn-out, When to Use It, and Why It Fails

An earn-out is a contractual clause in M&A transactions that conditions part of the purchase price on achieving future performance targets. The seller receives an upfront payment at closing and additional deferred payments if the company meets predefined targets—typically EBITDA, revenue, customer retention, or product launch—over a period of 1 to 4 years.

This mechanism addresses three structural problems in M&A:

• Information asymmetry: The seller knows the business better; the buyer distrusts optimistic projections. The earn-out transfers part of the execution risk to the more informed party.
• Valuation gap: When buyer and seller disagree on value, the earn-out helps bridge the gap without either side conceding immediately.
• Retention of critical talent: In services, technology, or proprietary know-how businesses, the earn-out keeps founders and key managers engaged during the transition.

However, the failure rate is high. SRS Acquiom (2022) analysis of 1,200 private equity transactions in the US shows that most earn-outs paid less than the maximum expected value, and many paid nothing. In Portugal, CMVM data on tender offers and reported transactions indicate that most earn-out clauses resulted in price adjustments below initial estimates.

The main causes of failure are concentrated in four areas:

1. Ambiguous metrics: Vague accounting definitions ("adjusted EBITDA," "recurring revenue") allow for divergent interpretations.
2. Control conflict: The buyer assumes operational management, but the seller depends on third-party decisions to achieve targets.
3. Strategic changes: The buyer changes the business model, pricing policy, or cost structure, making original targets unachievable.
4. Lack of governance: Absence of oversight committees, independent audits, or dispute resolution mechanisms.

This article provides the complete technical protocol for structuring earn-outs in M&A: from selecting metrics and calculation formulas to protective clauses, post-closing governance, and tax implications in Portugal. It is intended for CEOs, CFOs, M&A lawyers, and corporate finance advisors seeking to reduce litigation risk and increase the likelihood of full payment.

Why the Earn-out Became the Standard Mechanism in Mid-market Transactions

During the 2010s, the earn-out was seen as a niche tool, mainly used in high-uncertainty sectors—early-stage technology, founder-dependent professional services, companies with volatile track records. From 2018 onwards, it became mainstream. Deloitte M&A Trends data show that the percentage of global transactions with an earn-out component rose significantly from 2015 to 2022. In Portugal, APCRI analysis of private equity deals shows a high prevalence in transactions between €5 and €50 million.

Three factors explain this evolution:

1. Growing Divergence Between Seller Expectations and Buyer Risk Appetite

Abundant liquidity in the M&A market—fueled by record dry powder from private equity funds ($1.8 trillion globally, Preqin 2023)—drove up market valuation multiples. But post-pandemic macroeconomic volatility and rising interest rates increased risk aversion. Buyers want to pay for proven performance, not projections. Sellers, used to high multiples, refuse discounts. The earn-out resolves the impasse: the buyer pays a conservative multiple upfront and a premium multiple if targets are met.

2. Increasing Complexity of Digital and Recurring Business Models

SaaS companies, marketplaces, subscription models, and digital platforms present unique valuation challenges. Traditional metrics (EBITDA, cash flow) poorly capture the value of recurring customer bases, churn rates, lifetime value, or product-market fit. The earn-out aligns payment with empirical confirmation of retention, revenue expansion, and scalability. In Portugal, most technology company transactions between 2020-2023 included earn-outs based on ARR (Annual Recurring Revenue) or NRR (Net Revenue Retention), according to the Portuguese Startup Association.

3. Talent Scarcity and Dependence on Founding Teams

In knowledge-intensive sectors—consulting, engineering, software, healthcare—value resides in people, not tangible assets. The abrupt departure of founders or key managers quickly destroys value. The earn-out, combined with employment and non-compete agreements, acts as "golden handcuffs": it keeps critical talent engaged for 2-3 years, enough to transfer know-how, consolidate client relationships, and institutionalize processes. BCG studies indicate that acquired companies with earn-outs and founder retention have a 2.3x higher integration success rate.

In the Portuguese context, the prevalence of family businesses—which represent a significant share of GDP and employment (INE, 2022)—makes the earn-out especially relevant. Family business valuation for succession or sale to third parties often involves founders who want to "see to believe" before transferring full control. The earn-out allows for a gradual transition, with payment proportional to confirmation that the buyer can maintain or accelerate performance.

Types of Earn-out: Choosing the Right Structure for the Transaction

There is no one-size-fits-all earn-out model. The ideal structure depends on four variables: sector, company maturity, seller motivation, and buyer risk appetite. The following taxonomy covers most cases observed in mid-market transactions.

1. EBITDA or Operating Profit-based Earn-out

The most common metric (majority of cases, SRS Acquiom). The seller receives an additional payment if the company meets or exceeds a certain EBITDA during the earn-out period. Suitable for mature companies with stable track records and predictable margins.

Advantages: Widely understood metric, aligned with economic value creation, hard to manipulate if well defined.

Disadvantages: Vulnerable to cost allocation decisions (corporate overhead, transfer pricing, discretionary investments). Requires rigorous contractual definition of "adjusted EBITDA" and an exhaustive list of exclusions.

Sample clause: "The seller will receive €1 for every €1 of adjusted EBITDA above €5 million in each fiscal year of the earn-out period (2024-2026), up to a cumulative maximum of €3 million. Adjusted EBITDA = reported EBITDA minus integration costs, minus investments in international expansion approved by the Board, minus accounting adjustments resulting from changes in IFRS standards."

2. Revenue or Turnover-based Earn-out

Used when the buyer seeks aggressive growth and is willing to sacrifice margin temporarily. Common in technology sectors, marketplaces, and scaling companies.

Advantages: Objective metric, less subject to accounting manipulation, aligns seller with top-line growth.

Disadvantages: Ignores profitability; incentivizes the seller to accept marginal or unsustainable deals; may create conflict if the buyer changes pricing policy.

Critical protections: Define "eligible revenue" (exclude extraordinary discounts, related-party sales, non-recurring contracts); set a minimum gross margin floor; include an adjustment clause if the buyer changes pricing strategy.

3. Milestone-based Earn-out (Operational Milestones)

Payment conditional on achieving non-financial objectives: product launch, certification, signing a key contract, entering a new market. Used in life sciences, early-stage technology, or infrastructure projects.

Advantages: Aligns incentives with strategic plan execution; reduces subjectivity of financial metrics; suitable when future value depends on discrete events.

Disadvantages: Requires unambiguous definition of "milestone achieved"; vulnerable to disputes over interpretation; may incentivize the seller to achieve the milestone without regard for quality or sustainability.

Example: Medical software company acquired by a healthcare group. €2 million earn-out paid if: (i) CE-MDR certification obtained by 31/12/2024; (ii) contracts signed with 3 public hospitals by 30/06/2025; (iii) AI module launched in production by 31/12/2025. Each milestone is worth €666k, payment independent.

4. Hybrid Earn-out (Financial + Operational)

Combines financial metrics and operational milestones. Example: majority based on EBITDA, minority based on retention of key clients. Offers balance between profitability and strategic execution.

Advantages: Reduces risk of one-dimensional optimization (e.g., seller sacrifices margin to achieve revenue); aligns multiple objectives.

Disadvantages: Increases calculation and audit complexity; requires more robust governance.

5. Earn-out with Floor, Target, and Cap

Three-tier structure: guaranteed minimum payment (floor), target payment, and maximum payment (cap). Allows for asymmetric sharing of upside and downside.

Example: 3-year earn-out with a €4 million target (paid if average EBITDA = €6M). If average EBITDA is below €5M, seller receives only €2M (floor). If average EBITDA exceeds €7M, seller receives €6M (cap). Between €5M and €7M, payment is linear.

This structure is common in transactions where the buyer assumes high risk (turnaround company, volatile sector) but wants to share upside if performance exceeds expectations.

Technical Architecture of the Earn-out: Metrics, Calculation Formulas, and Measurement Periods

The effectiveness of an earn-out depends on three technical elements: unambiguous metric definition, transparent calculation formula, and appropriate measurement period. Failure in any of these is the primary cause of disputes.

Metric Definition: The "Adjusted EBITDA" Problem

The term "EBITDA" seems objective. It is not. Accounting standards (IFRS, US GAAP, local standards) allow multiple interpretations of depreciation, amortization, provisions, restructuring costs, and extraordinary items. In M&A transactions, "adjusted EBITDA" is often defined in the contract—but not rigorously enough.

Poor clause: "Adjusted EBITDA will be calculated in accordance with accounting practices consistent with those used in the last 3 years."

Problem: Who defines "consistent"? If the buyer changes accounting software, provisioning policy, or corporate cost allocation, is consistency breached?

Robust clause:

"Adjusted EBITDA = Operating result + Depreciation and amortization + Non-recurring provisions, excluding: (i) post-acquisition integration costs above €X; (ii) investments in new markets approved in writing by the Earn-out Committee; (iii) changes in accounting policies not required by law; (iv) corporate service costs allocated to the acquired company above €Y per year. Calculation will be audited by [Big Four] and follow IFRS standards in force at closing, except for mandatory changes."

This clause anticipates opportunistic behavior: it prevents the buyer from inflating integration costs, allocating excessive overhead, or changing accounting policies to reduce reported EBITDA.

Calculation Formulas: Linearity, Tiers, and Accelerators

The relationship between performance and payment can be linear, tiered, or accelerated. Each structure creates different incentives.

Linear: Payment proportional to performance. Example: €1 earn-out for every €1 of EBITDA above threshold. Simple, transparent, but does not capture risk asymmetry.

Tiers: Payment increases in steps. Example:

• EBITDA €5-6M: earn-out = €1M
• EBITDA €6-7M: earn-out = €2M
• EBITDA >€7M: earn-out = €3M

Advantage: simplicity. Disadvantage: creates a "cliff effect"—the seller may prefer €5.9M EBITDA (receives €1M) to €6.1M (receives €2M but requires more effort).

Accelerators: Payment grows exponentially above target. Example: if EBITDA exceeds €7M, seller receives a significant share of the earn-out target. Used when the buyer wants to incentivize exceptional performance.

Measurement Periods: Annual, Cumulative, or Average

The measurement period affects volatility and risk.

Annual independent: Earn-out calculated and paid year by year. Seller receives partial payment even if one year is weak. Reduces seller risk but allows the buyer to "sacrifice" a year to reduce total payment.

Cumulative: Earn-out based on total performance over the period (e.g., cumulative 3-year EBITDA >€18M). Seller is paid only if aggregate performance meets the target. Increases seller risk but reduces annual manipulation.

Average: Earn-out based on average performance (e.g., 3-year average EBITDA >€6M). Smooths volatility, protects the seller from exceptionally weak years, but may penalize concentrated exceptional performance.

In Portugal, analysis of M&A contracts by the CMVM indicates a prevalence of cumulative structures (majority) in transactions above €10M, and annual independent structures (majority) in transactions below €10M. The choice reflects risk appetite: buyers of larger companies prefer structures that reduce partial payments; sellers of smaller companies require annual cash flow visibility.

Protective Clauses: How to Prevent Opportunistic Behavior and Ensure Fairness

The earn-out creates a principal-agent problem: the buyer controls the company, but the seller depends on its performance. Without contractual protections, the buyer may manipulate results, change strategy, or simply manage the company to minimize payment. The following clauses are critical.

1. Best Efforts or Commercially Reasonable Efforts Clause

Obliges the buyer to manage the acquired company consistently with reasonable commercial practices, without deliberate actions to reduce the earn-out.

Standard clause: "The buyer undertakes to operate the acquired company in line with prudent and commercially reasonable management practices, not taking actions with the primary purpose of reducing the earn-out payment."

Problem: "Commercially reasonable" is vague. What is reasonable for the buyer (e.g., cutting marketing investment to improve margin) may harm a revenue-based earn-out.

Reinforced clause: "The buyer will operate the acquired company in line with the attached business plan (Annex A), including minimum investment levels in [marketing, R&D, sales team]. Any deviation above a significant threshold from the plan requires prior approval from the Earn-out Committee. If deviation is approved and results in targets not being met, the earn-out will be adjusted by an independent expert."

2. Operational Independence Clause

Limits the buyer's ability to integrate the acquired company in ways that distort earn-out metrics.

Example: "During the earn-out period, the acquired company will maintain: (i) independent accounting and billing systems; (ii) dedicated sales teams; (iii) separate brand and market identity. The buyer may not: (a) transfer clients or contracts to other group entities; (b) allocate corporate costs above €X per year; (c) change pricing policies without the seller's consent."

This clause is common in professional services transactions, where premature integration undermines the ability to measure standalone performance.

3. Adjustment Clause for Strategic Changes

Protects the seller if the buyer changes the business model in a way that makes the earn-out unachievable.

Example: "If the buyer changes the acquired company's business model—including but not limited to: switching from B2B to B2C, changing from subscription to perpetual license, discontinuing product lines responsible for a significant share of revenue—the earn-out will be recalculated by an independent expert based on as-is performance projections, or paid in advance at net present value with a significant discount."

4. Acceleration Clause for Change of Control

If the buyer sells the acquired company during the earn-out period, the original seller receives accelerated payment.

Example: "If the buyer sells a significant share of the acquired company's capital to third parties during the earn-out period, the seller will immediately receive: (i) the earn-out target at net present value; or (ii) a percentage of the sale price equivalent to the earn-out target / initial enterprise value ratio, whichever is higher."

This clause prevents the buyer from flipping the company quickly, capturing upside without paying the earn-out.

5. Audit and Information Access Clause

Ensures the seller can verify the earn-out calculation.

Example: "The seller will have quarterly access to: (i) the acquired company's financial statements; (ii) management reports and operational KPIs; (iii) commercial contracts and policy changes. The seller may, once per year and at their own expense, hire an independent auditor to verify the earn-out calculation. If a discrepancy above a significant threshold is found, the buyer will pay audit costs."

Post-closing Governance: The Earn-out Committee and Dispute Resolution Mechanisms

Even with robust clauses, disputes are inevitable. The difference between successful and failed earn-outs lies in the existence of corporate governance structures that allow disagreements to be resolved before escalating to litigation.

Earn-out Committee: Composition and Mandate

Three-member structure: one representative from the buyer, one from the seller, one independent (typically a corporate finance advisor or auditor). Meets quarterly to:

• Review performance vs. earn-out targets
• Approve deviations from the business plan
• Resolve disputes over clause interpretation
• Validate adjusted EBITDA or other metric calculations

Committee decisions are binding except in cases of fraud or manifest error. Costs are shared 50/50.

Tiered Dispute Resolution Mechanism

Typical structure in sophisticated M&A contracts:

1. Direct negotiation (15 days): Buyer and seller CFOs attempt resolution.
2. Earn-out Committee (30 days): Escalation to the Committee, which issues a binding opinion.
3. Independent expert (60 days): If the Committee cannot reach consensus, the matter is submitted to a Big Four or valuation boutique. Decision is final and binding.
4. Arbitration (only in case of fraud or material breach): Arbitration under CAAD (Administrative Arbitration Center) or ICC rules, in Lisbon, Portuguese language.

This mechanism avoids courts (slow, expensive, public) and maintains a functional relationship between parties.

Seller's Role in Post-acquisition Management

How much operational control should the seller retain? Three models:

Model 1 — Seller as CEO/COO: Maintains full operational control, reports to a buyer-dominated Board. Suitable when the seller is critical for execution and the earn-out is EBITDA-based.

Model 2 — Seller as Consultant/Advisor: No operational control, but veto rights on strategic decisions (pricing, M&A, product discontinuation). Suitable when the buyer wants rapid integration but needs the seller's know-how.

Model 3 — Seller with No Operational Role: Observer only, with information rights. Suitable when the earn-out is milestone-based (regulatory approvals, contracts) and the seller lacks management skills.

Data from 340 transactions analyzed by Harvard Business School indicate that earn-outs with the seller in an active operational role (Model 1) have a significantly higher full payment rate, versus a lower rate when the seller has no role (Model 3). However, interpersonal conflicts are 2.1x more frequent in Model 1.

Practical Implementation: 90-day Roadmap to Structure an Earn-out in M&A

Structuring a robust earn-out is not a last-minute exercise. It requires planning, rigorous financial modeling for M&A, and alignment between legal, financial, and operational teams. The following protocol covers from initial negotiation to closing.

Phase 1 — Diagnosis and Conceptual Design (Weeks 1-3)

Objective: Determine if an earn-out is appropriate and, if so, which structure.

Activities:

• Valuation gap analysis: Quantify the difference between seller expectation and buyer offer. If the gap is significant, the earn-out is a natural candidate.
• Identification of value drivers: Which metrics best capture future value creation? EBITDA (mature companies), recurring revenue (SaaS), client retention (services), product milestones (technology).
• Execution risk assessment: What is the probability of meeting targets? If below a certain threshold, the earn-out is a bet, not an alignment mechanism.
• Scenario simulation: Use scenario analysis (base, optimistic, pessimistic) to model earn-out payments and impact on total buyer return.

Deliverable: Term sheet with conceptual earn-out structure (metric, period, target, cap, key protections).

Phase 2 — Financial Modeling and Stress-testing (Weeks 4-6)

Objective: Build a financial model simulating the earn-out under multiple scenarios.

Activities:

• Earn-out model construction: Excel with inputs (EBITDA, revenue, margins), calculation formula, outputs (annual payment, NPV of earn-out). Include sensitivities to growth, margin, discount rate.
• Tax impact analysis: Model earn-out taxation for the seller (capital gains vs. income, deferral) and buyer (deductibility, tax goodwill).
• Opportunistic behavior testing: Simulate scenarios where the buyer manipulates metrics (e.g., increases cost allocation, changes provisioning policy). How much of the earn-out is destroyed? Which clauses prevent this?
• Market benchmarking: Compare proposed structure with comparable transactions (same sector, size, geography). Data from deal databases (Capital IQ, PitchBook) or Big Four M&A reports.

Deliverable: Complete financial model + risk analysis memo.

Phase 3 — Negotiation and Drafting of Clauses (Weeks 7-10)

Objective: Translate the conceptual structure into unambiguous contractual language.

Activities:

• Metric definition: Draft a complete definition of "adjusted EBITDA," "eligible revenue," or other metrics. Include numerical examples in an annex.
• Drafting of protective clauses: Best efforts, operational independence, adjustment for change of control, information access.
• Governance structuring: Composition of the Earn-out Committee, meeting frequency, dispute resolution mechanism.
• Negotiation of trade-offs: Seller wants a high floor, buyer wants a low cap. Seller wants operational independence, buyer wants rapid integration. Resolve through asymmetric structure (e.g., medium floor + high cap if seller accepts integration).

Deliverable: Draft earn-out clauses for the SPA (Sale and Purchase Agreement).

Phase 4 — Earn-out Due Diligence and Validation (Weeks 11-12)

Objective: Confirm that earn-out metrics are auditable and that information systems support calculation.

Activities:

• Accounting systems audit: Confirm that the acquired company can report earn-out metrics monthly. If adjusted EBITDA requires complex reconciliations, dispute risk increases.
• Historical validation: Recalculate earn-out metrics for the past 3 years using the contractual definition. If results diverge significantly from historical reports, revise the definition.
• Independence testing: If the clause requires independent systems, confirm technical feasibility (ERP, CRM, billing). Estimate costs of maintaining independence.

Deliverable: Earn-out due diligence report + final adjustment list.

Phase 5 — Closing and Post-acquisition Setup (Week 13+)

Objective: Operationalize the earn-out and establish governance.

Activities:

• First Earn-out Committee meeting: Align interpretation of clauses, agree on reporting calendar, define quarterly report templates.
• Reporting systems setup: Configure dashboards with earn-out KPIs, automate calculations where possible, establish quarterly audit process.
• Stakeholder communication: Inform teams (sales, finance, operations) about the existence of the earn-out and implications for operational decisions. The stakeholder management protocol in M&A is critical to avoid information leaks or demotivation.

Deliverable: Earn-out playbook (operational document with processes, responsibilities, calendar).

Portuguese Context: Tax, Legal Implications, and Financing Opportunities

Taxation of Earn-outs in Portugal: Seller and Buyer

Taxation of earn-outs in Portugal is not explicitly regulated, creating uncertainty. The practice of the Tax Authority and recent case law establish the following principles:

For the seller (individual):

• Capital gains (Category G): If the earn-out is considered part of the sale price, it is taxed as a capital gain (majority inclusion, marginal rate up to a significant threshold → maximum effective rate significant). Applicable if payment is certain and only deferred in time.
• Income (Category B or E): If the earn-out is contingent and the seller retains an operational role, the Tax Authority may qualify it as employment or business income (rate up to a significant threshold + social security). Higher risk if the earn-out is based on the seller's individual performance.
• Tax deferral: The seller may opt to defer earn-out taxation until actual receipt (cash basis), but must declare in the closing year and pay compensatory interest if challenged by the Tax Authority.

For the seller (corporate):

• Earn-out is taxed as a capital gain (CIT at a significant rate, or lower if SME). Accounting recognition follows IFRS 15 (recognize when probable and measurable), but for tax purposes, deferral until receipt may apply.

For the buyer:

• Earn-out paid increases acquisition cost and, consequently, tax goodwill. Goodwill amortization is deductible for CIT (1/20 per year, i.e., significant per year over 20 years).
• If the earn-out is classified as remuneration (seller is an employee), it is deductible as an operating cost (significant deductible in the year of payment), but subject to social security.

Practical recommendation: Include in the SPA an agreed tax qualification clause ("the parties agree that the earn-out constitutes part of the purchase price, taxable as a capital gain"), and obtain an advance tax ruling from the Tax Authority if the earn-out value exceeds €1M. Cost: €2,000-5,000, timeframe: 90-150 days.

Legal Framework: Commercial Companies Code and Creditor Protection

In Portugal, earn-outs structured as contingent liabilities may be subject to the Companies Code requirements:

• Article 35 (ancillary contributions): If the seller retains operational obligations, it may constitute an ancillary contribution, requiring statutory provision.
• Article 33 (supplementary contributions): If the earn-out is paid in shares (equity earn-out), it may require general meeting approval and shareholders' pre-emptive rights.
• Creditor protection: If the acquiring company records a high contingent liability (> significant of equity), creditors may require guarantees or oppose dividend distributions.

Mitigation clause: "The earn-out constitutes a conditional obligation of the buyer, not enforceable until conditions are met. It does not constitute debt for solvency ratios or bank covenant purposes until it becomes due."

Financing Opportunities: Earn-out and Leverage

Banks and debt funds treat earn-outs conservatively in credit analysis:

• Debt/EBITDA: Earn-out is generally excluded from financial debt if contingent. If certain (only deferred), it may be included at present value.
• Collateral: Earn-out is rarely accepted as collateral, as it is contingent and hard to enforce.
• Creative financing structures: Some debt funds

Questions for Management

• What concrete decision should this topic unlock?
• What internal data confirm that the opportunity is a priority?
• Who is responsible for execution, measurement, and review of progress?
• What risk increases if the company delays the decision?
• What capabilities must exist before investing?

These questions make the article more useful for decision-makers and clearer for AI-based response engines: there is an entity, Portuguese context, problem, decision criterion, and next step.

Related Readings

• due diligence in M&A
• M&A in Portugal
• earn-out in M&A
• market multiples
• company valuation
• EBITDA
• valuation

Sources

For further context and validation, consult relevant public and institutional sources for this topic:

• Banco de Portugal - Statistics and Companies
• CMVM - Capital Markets
• IAPMEI - Business Revitalization