Forensic Accountants for Contractual Disputes

Commercial disputes often turn on financial questions that solicitors can't answer from the pleadings alone. How much profit did the claimant actually lose? Was the defendant's breach the real cause of the downturn, or was the business already struggling? What would have happened if the contract had been performed? These are forensic accounting questions, and getting them right is usually what determines the settlement figure or the court's award of damages.

At Jack Ross, our forensic accountants have worked on contractual disputes across manufacturing, construction, professional services, retail and technology sectors since 1948. We act as expert witnesses, single joint experts, and advisory experts - and we're as comfortable in arbitration as we are in the High Court.

Commercial Dispute Resolution and Forensic Accounting

Commercial dispute resolution covers the full range of methods used to resolve business conflicts - from negotiation and mediation through to arbitration and litigation. Forensic accountants fit into every stage of that process. Before proceedings, we help solicitors assess quantum so they can advise their client on the strength of a claim or counterclaim. During proceedings, we prepare expert reports that quantify the financial loss and withstand cross-examination. In mediation and arbitration, we present our analysis directly to the mediator or tribunal.

The common thread is that someone needs to put a defensible number on the financial impact. A forensic accountant with experience of commercial dispute resolution brings the analytical rigour to do that - reviewing financial statements, modelling counterfactuals, and presenting findings in a way the court or tribunal can rely on.

Types of Contractual Disputes

Breach of contract. The most common category. A supplier fails to deliver, a distributor wrongfully terminates, a contractor walks off site. The forensic accountant's job is to quantify the loss of profits the claimant would have earned had the contract been performed. This involves building a counterfactual financial model using pre-breach trading data, applying appropriate margins, and deducting costs saved and benefits received. Where the breach relates to a specific contractual obligation, the damages calculation must align with the scope of that obligation.

Supply quality disputes. When goods or services fall below the contractually agreed standard, the financial consequences can extend far beyond the cost of the defective items. The claimant may face rejection costs, replacement sourcing costs, production downtime, lost customer contracts, and reputational damage. A forensic accountant traces each head of loss back to the supply failure and quantifies it separately - critical where the defendant argues that some losses are too remote.

Construction and engineering disputes. Delays, defective work, disputed variations, and liquidated damages claims are common in the construction sector. The forensic analysis often involves assessing cost overruns against the original budget, valuing delay by reference to lost revenue or additional financing costs, and evaluating competing claims and counterclaims. These cases frequently involve expert determination clauses in the contract, requiring a different procedural approach.

Professional negligence. Where a professional adviser - accountant, surveyor, IT consultant - has given negligent advice that caused financial loss, the forensic accountant calculates the difference between the client's actual position and where they would have been with competent advice. The scope of duty analysis from Manchester Building Society v Grant Thornton [2021] now governs the recoverability of those losses. See our professional negligence page for more on this.

How We Quantify Financial Loss in Contractual Disputes

Every damages calculation starts with the but-for test: what would have happened if the breach hadn't occurred? The forensic accountant builds the counterfactual from hard data - three to five years of financial statements, management accounts, VAT returns, bank statements, and any pre-breach forecasts or budgets. Industry benchmarks and comparable company data help validate the assumptions.

The calculation follows a structured approach:

• Establish but-for revenue and margin (what the claimant would have earned)
• Deduct actual revenue and margin during the loss period
• Adjust for costs saved, alternative revenue earned, and mitigation steps taken
• Consider wasted expenditure where lost profits can't be reliably projected (per Anglia Television v Reed [1972])
• Apply a discount rate where future losses are capitalised
• Account for taxation of the damages award where relevant

The financial analysis must address remoteness. Under Hadley v Baxendale, losses are recoverable only if they arise naturally from the breach or were within the reasonable contemplation of both parties at the time of contracting. The forensic accountant must be ready to explain why each head of loss meets that test - and to calculate alternative figures if the court takes a narrower view.

Where both sides have instructed experts, the court typically directs them to meet and produce a joint statement identifying areas of agreement and disagreement. This litigation support process often narrows the quantum dispute dramatically, focusing the trial on a handful of contested assumptions rather than the entire model.

Alternative Dispute Resolution

Not every contractual dispute goes to court. ADR methods - mediation, arbitration, and expert determination - are increasingly the preferred route, especially where the parties want to preserve a commercial relationship or resolve the dispute faster and more cost-effectively than litigation allows.

Mediation. The forensic accountant prepares a concise financial summary for the mediator, setting out the quantum case clearly. In mediation, the ability to present a credible financial position is often what drives settlement. We attend mediations to answer financial questions in real time and to test settlement proposals against the modelled outcomes.

Arbitration. International and domestic arbitration proceedings follow their own procedural rules, but the forensic accountant's role is similar to litigation: prepare a formal report, attend hearings, and give evidence. In international arbitration, the expert may need to address accounting standards from multiple jurisdictions.

Expert determination. Some contracts include clauses requiring disputes to be resolved by expert determination rather than litigation or arbitration. Here, the appointed expert makes a binding decision. The forensic accountant may be the appointed expert or may advise a party on the financial aspects of the determination.

Case Study: Supply Quality Dispute

We were instructed as single joint expert in a dispute between a sole-trader manufacturing business and its primary raw materials supplier. The supplier had changed its production process, and the quality of materials delivered over a six-month period had deteriorated significantly. The manufacturer's products began failing quality checks, leading to customer rejections, lost contracts, and ultimately the failure of the business.

The key challenge was quantifying the loss of profits attributable specifically to the supply quality issue, as opposed to broader market conditions and the business owner's own commercial decisions. Our financial analysis covered three years of pre-dispute trading, the six-month deterioration period, and the subsequent wind-down. We examined the direct impact on sales and customer retention, the additional costs of sourcing replacement materials, and the longer-term reputational damage to the brand.

We prepared a comprehensive CPR Part 35 report setting out three valuation scenarios: full causation (all losses attributable to supply failure), partial causation (with adjustments for pre-existing market decline), and a minimum figure stripping out any losses the defendant could credibly argue were unrelated. The report also addressed the manufacturer's duty to mitigate and whether reasonable steps had been taken.

The joint statement narrowed the dispute from a range of £180,000 to £420,000 down to a range of £260,000 to £310,000. The case settled at mediation for £285,000 - within the range we'd identified as most likely. The SJE approach saved both parties the cost of a contested trial and delivered a resolution in under nine months.

The Single Joint Expert's Role

In many contractual disputes, the court will direct the parties to appoint a single joint expert rather than each side instructing their own. This is common in fast-track cases and in multi-track cases where the quantum issues are complex but not fundamentally contested.

The SJE's duty is to the court, not to either party. We receive questions from both sides, prepare a single report addressing all of them, and attend court to give evidence if needed. Impartiality isn't just a professional obligation - it's what makes the SJE's evidence credible. Where we identify that a party-appointed approach would be more appropriate (typically where fraud or deliberate concealment is alleged), we say so at the outset.

How to Instruct Us

Our forensic accounting services cover contractual disputes of all sizes, from sole-trader supply disputes to multi-million-pound commercial litigation. For an initial discussion about a forensic accounting instruction, contact Jack Ross or call 0161 832 4451. We provide preliminary quantum assessments to help solicitors evaluate whether a claim or counterclaim has sufficient financial substance to pursue. See also our pages on commercial damages quantification and loss of profits claims.