Litigation Support Accountant | Commercial Damages UK

When commercial litigation turns on financial quantum, the legal team needs a practice that can build a credible, defensible quantification of loss. Our litigation support services cover a wide range of that work: calculating lost profits and loss of earnings, quantifying professional negligence damages, analysing business interruption claims, and preparing financial evidence for breach of contract and breach of warranty disputes. We work alongside lawyers and law firms, either in an advisory capacity behind the scenes or as a named expert under CPR Part 35.

What Litigation Support Means in Practice

There is an important distinction between litigation support and expert witness work. An advisory role involves working with the instructing legal team behind the scenes. Their work is privileged. They help the legal team understand the financial issues, assess the strengths and weaknesses of the client's claim, prepare cross-examination questions for the opposing witness, and produce financial analysis that informs settlement negotiations. Key terms used on this page are defined in our glossary.

An expert witness, by contrast, owes a duty to the court under CPR Part 35.3 and provides an independent opinion that is disclosed to all parties. The distinction matters for engagement structure, privilege, and the scope of the work.

In many cases, the same forensic accounting professional performs both roles sequentially: providing advisory support during the pre-action and disclosure phases, and then being appointed as the named witness for trial. Where this transition is planned, the engagement must be structured carefully to maintain the integrity of that role. Any analysis produced during the advisory phase that informs the disclosed report should form part of the working papers.

What does litigation support cover?

Litigation services from a forensic accountant cover the financial side of any legal dispute. The work spans pre-issue investigation, schedules of loss, expert reports under CPR Part 35, joint statements, and oral evidence at trial. Lawyers instruct us across the full range of proceeding types: commercial claims, professional negligence, shareholder disputes, fraud, insurance recoveries, matrimonial finance, and confiscation under the Proceeds of Crime Act.

• Pre-issue advice. Reviewing the financial merits of a potential claim before proceedings start. Often the most valuable stage - if the numbers don't add up, the case shouldn't be issued.
• Quantum analysis. Calculating the financial loss the claimant has suffered, broken down by category and supported by source documents.
• Expert reports. Drafting CPR-compliant reports for the court, addressed to the judge rather than the instructing lawyer.
• Schedules of loss and counter-schedules. Detailed line-by-line schedules that lawyers use to particularise damages claims.
• Mediation and settlement support. Modelling settlement scenarios and tax consequences during ADR proceeding stages.
• Court attendance. Giving oral evidence and being cross-examined on the report's methodology and conclusions.

The deliverable in every legal dispute is the same: a financial analysis a judge can rely on. Whether the dispute settles or goes to trial, the quality of the underlying numbers determines the outcome.

Loss of Profits Quantification

The "but for" test sits at the foundation of every loss of profits claim. The question is simple: what would the claimant's financial position have been but for the defendant's wrongful act? The answer, however, requires detailed financial modelling.

Building the counterfactual involves constructing a credible projection of how the business would have performed in the absence of the breach, negligence or tort. This typically draws on:

• Pre-breach trend analysis: using 3 to 5 years of historical performance to project the trajectory the business would have followed
• Industry benchmarks: comparing the claimant's performance against sector data to test whether the projected trajectory is reasonable
• Management projections: where the business had budgets or forecasts prepared before the breach, these provide useful evidence of expected performance, though they must be assessed with appropriate scepticism
• Comparable businesses: where available, the performance of similar businesses during the same period can corroborate the counterfactual

The difference between the counterfactual (what would have happened) and the actual results (what did happen) is the gross loss. From this, the forensic accountant must deduct any benefits received (insurance proceeds, alternative revenue streams) and any costs saved as a result of the breach.

Mitigation is a critical element. The claimant has a duty to take reasonable steps to reduce their loss. We assess whether the mitigation was reasonable and deduct any mitigated amounts. Failure to mitigate can significantly reduce the recoverable loss, and the defendant's side will focus heavily on this issue.

Professional Negligence Claims

Professional negligence claims against accountants, solicitors, financial advisers and surveyors require forensic accounting expertise to quantify the financial consequences of the negligence. The measure of loss is the difference between the client's actual position and the position they would have been in had the professional not been negligent.

The scope of duty analysis is essential. Manchester Building Society v Grant Thornton [2021] UKSC 20 recalibrated the approach established in South Australia Asset Management Corp v York Montague Ltd [1997] (SAAMCO), clarifying that the defendant is liable only for losses falling within the scope of their duty, not for all losses that would not have occurred but for their negligence. The forensic accountant's quantification must be framed within that scope.

Related topics include loss of a chance claims (Allied Maples Group v Simmons and Simmons [1995]), tax gross-up of damages, and contributory negligence reductions under the Law Reform (Contributory Negligence) Act 1945. Each requires the quantification to be presented on alternative bases so the tribunal can apply the appropriate reduction.

Business Interruption Insurance Claims

Business interruption (BI) insurance claims require specialist accounting analysis because the policy wording creates its own definitions that do not align with standard accounting terminology.

The most common source of disputes is the definition of "gross profit" in the policy. Under most BI policies, this means turnover less specified variable costs (often called "uninsured working expenses"), which differs from the definition in the accounts. Applying the wrong definition produces the wrong figure.

The indemnity period, trends clause and savings provisions are all policy-specific. The FCA Business Interruption Test Case [2021] UKSC 1 clarified coverage issues, but the quantification principles apply to all BI claims. Our role is typically to prepare the claim for the policyholder's legal team or to review it on behalf of the insurer. Either way, the analysis must follow the policy wording.

Commercial Damages and Contractual Disputes

Beyond loss of profits and professional negligence, forensic accountants across the UK advise on and provide quantum evidence in personal injury, matrimonial finance and a range of commercial disputes:

Breach of warranty claims in M&A transactions: Where the seller's warranties about the target company prove false, the buyer's loss is typically the difference between the price paid and the true value of the business at completion. This requires a retrospective business valuation at the completion date, incorporating the information that was not disclosed or was misstated.

Restrictive covenant breaches: Quantifying diverted profits where an employee or vendor has breached a non-compete or non-solicitation clause. The challenge is separating profits that were genuinely diverted from those that the competitor would have won regardless.

Partnership and joint venture dissolution: Unwinding the financial relationship, valuing the partnership's assets and liabilities, and determining each partner's entitlement. Where the partnership agreement does not address dissolution adequately, the Partnership Act 1890 default provisions apply.

Wasted expenditure: Where lost profits cannot be reliably calculated, the claimant may recover expenditure incurred in reliance on the contract. Anglia Television v Reed [1972] established this alternative measure of loss. We identify and quantify the wasted costs, and can assist in ensuring that only expenditure genuinely incurred in reliance on the contract is included.

Our Approach to Quantification

As chartered accountants, we work to the civil standard of proof (balance of probabilities) unless instructed on a criminal matter. Our forensic team has expertise across every stage of the litigation process, from regulatory matters and compliance reviews through to arbitration and insolvency proceedings. Every assumption in our quantification is documented, sourced, and justified. Where the evidence supports more than one reasonable conclusion, we present a range rather than a single figure that implies false precision.

We investigate the financial aspects of each case with rigour. Cross-examination is part of the process, and our quantifications are built to withstand it. Where we provide expert opinion in an advisory capacity, we apply the same rigour to our internal analysis as we would to a formal report, because the analysis may ultimately inform the disclosed evidence.

Where the dispute involves suspected fraud, asset recovery or financial irregularity, our financial investigations and quantification work often run in parallel. We can provide both services, subject to proper engagement structure to maintain the independence of the disclosed opinion. Taxation of damages awards is another area where we advise - the interaction between compensation and trading income creates complex legal and financial questions.

To discuss litigation matters, contact Jack Ross at our Manchester office or call 0161 832 4451. We also support London-based law firms, and their clients with litigation work across England and Wales.