How an Accounting Expert Witness Quantifies Loss of Profits in a Commercial Claim

Loss of profits can be an important issue in a commercial dispute where one party alleges that an event caused its business to earn less than it otherwise might have earned. Examples may include alleged breaches of contract, business interruptions, or other events said to have affected trading performance.

An accounting expert witness may be instructed to examine the financial evidence and provide an independent analysis of the alleged loss. The appropriate approach depends on the facts of the dispute, the available records, the period under consideration, and the questions within the expert's instructions.

This article explains how an accounting expert witness may approach the quantification of loss of profits in a commercial claim.

What Is Loss of Profit?

Loss of profit generally refers to profit that a claimant says it would have earned if the event giving rise to the claim had not occurred.

The analysis is not necessarily the same as comparing revenue before and after an alleged event. Revenue does not represent profit because a business may incur costs in generating additional sales.

For example, a loss of profits calculation may need to consider:

• The revenue that is alleged to have been lost
• The costs that would have been incurred in generating that revenue
• The relevant profit margin
• Costs that may have been avoided because the sales did not occur
• Other factors that may have affected trading performance during the relevant period

The appropriate calculation depends on the circumstances and the financial evidence available.

The Role of an Accounting Expert Witness

An accounting expert witness may be asked to analyse financial information and provide an independent opinion on accounting or financial issues within their expertise.

In a loss of profits dispute, this may involve reviewing financial records, examining the basis of the claimed loss, and assessing the methodology used to quantify it.

Depending on the instructions, an accounting expert may:

1. Review relevant financial records
2. Consider the financial circumstances of the business
3. Examine the basis of the claimed loss
4. Assess relevant assumptions and calculations
5. Carry out appropriate financial analysis
6. Identify material limitations in the available evidence
7. Explain the methodology and conclusions in an expert report

The expert should distinguish between factual information, assumptions provided for the purpose of the analysis, and their own professional opinion.

What Financial Evidence May Be Relevant?

The evidence required will vary between cases. Depending on the dispute, an accounting expert witness may review documents such as:

• Annual accounts
• Management accounts
• Budgets and forecasts
• General ledgers
• Sales records
• Purchase records
• Invoices
• Payroll information
• Bank statements
• Customer and supplier records
• Contracts and commercial agreements
• Business interruption records
• Previous trading results
• Information concerning comparable periods

Non-financial evidence may also be relevant where it helps explain the circumstances of the alleged loss.

The objective is not necessarily to review every available document. The relevant evidence will depend on the issues the expert has been instructed to address.

Establishing the Hypothetical Financial Position

A loss of profits calculation may require consideration of what the claimant's financial position might have been if the relevant event had not occurred.

This is commonly approached through a hypothetical or counterfactual scenario.

The analysis may involve comparing:

The financial position actually achieved

with

The financial position that is said to have been achieved without the relevant event

The difference between those positions may form part of the claimed loss, subject to the facts of the case, the evidence available, applicable legal principles, and the expert's instructions.

Why the Counterfactual Requires Care

A hypothetical financial position cannot necessarily be established simply by extending historical results.

A business may have experienced changes in:

• Customer demand
• Pricing
• Competition
• Capacity
• Staffing
• Costs
• Supply arrangements
• Market conditions
• Regulation
• Business strategy

These factors may need to be considered when assessing whether projected sales or profits are supported by the available evidence.

Historical performance can be relevant, but it does not necessarily establish what would have happened in the absence of the alleged event.

Analysing Historical Trading Performance

Historical financial information can provide relevant evidence when assessing a loss of profits claim.

An accounting expert may examine trading results over appropriate periods to identify patterns in:

• Revenue
• Gross profit
• Operating costs
• Profit margins
• Customer activity
• Product or service performance
• Seasonal fluctuations

The appropriate comparison period depends on the circumstances.

For example, where a business experiences significant seasonal fluctuations, comparing equivalent periods from previous years may provide different information from comparing consecutive months.

Historical results should therefore be considered alongside other relevant evidence rather than treated as conclusive on their own.

Assessing Potential Lost Revenue

A loss of profits calculation may require an assessment of the revenue that the claimant says would otherwise have been generated.

Depending on the case, an expert may consider evidence such as:

• Existing customer orders
• Historical sales patterns
• Contractual commitments
• Sales pipelines
• Customer retention rates
• Capacity constraints
• Previous growth rates
• Pricing records
• Relevant market information

The evidential support for each assumption will depend on the particular circumstances.

Where projected revenue relies substantially on assumptions rather than contemporaneous records, those assumptions may need to be identified and their significance explained.

Considering Costs and Profit Margins

Lost revenue is not necessarily the same as lost profit.

If a business would have incurred costs in generating additional revenue, those costs may need to be considered when calculating the resulting profit.

Depending on the circumstances, relevant costs may include:

• Materials
• Stock
• Subcontractor costs
• Sales commissions
• Distribution costs
• Additional staffing
• Transaction fees
• Other variable costs

Some costs may continue regardless of changes in revenue, while others may vary with the level of business activity.

Fixed and Variable Costs

The distinction between fixed and variable costs can therefore be relevant to a loss of profits calculation.

A cost that would have been incurred regardless of additional sales may need to be considered differently from a cost that would only arise if those sales occurred.

The treatment of individual costs should be based on the circumstances and supporting financial evidence rather than on labels alone.

Testing Assumptions and Alternative Scenarios

Loss of profits calculations can depend on a number of assumptions.

An accounting expert may therefore examine whether the financial model is consistent with the available evidence. This may include assumptions concerning:

• Revenue growth
• Sales volumes
• Pricing
• Gross margins
• Operating costs
• Capacity
• Customer demand
• Duration of the alleged loss

Where appropriate, an expert may also consider alternative scenarios.

Sensitivity Analysis

Sensitivity analysis can be useful where a calculation depends on assumptions that could reasonably vary.

For example, an expert may examine how the calculated loss changes if an assumed sales volume or profit margin is different.

This does not determine which assumption is legally correct. It can instead show how the financial calculation changes when particular variables are altered.

Considering Other Financial Effects

Depending on the issues in dispute and the scope of the instructions, the analysis may also need to consider events that affected the alleged loss.

For example, the business may have:

• Recovered some lost sales
• Obtained alternative customers
• Used alternative suppliers
• Reduced certain costs
• Rescheduled production
• Continued trading through another channel

These matters may affect the financial calculation where supported by the evidence.

Whether a particular action amounts to legal mitigation is a matter for the appropriate legal analysis. An accounting expert may instead address the financial consequences of relevant factual scenarios within their area of expertise.

Avoiding Double Counting

A loss of profits analysis may also need to consider whether different elements of a claim overlap.

For example, a claimant may seek compensation for lost profits while also claiming other financial losses. If the same financial effect is included more than once, there may be a risk of duplication.

An accounting expert may therefore review the calculations for potential overlaps within the scope of their instructions.

This can be particularly relevant where several heads of financial loss are being considered together.

How the Analysis May Be Presented in an Expert Report

An expert report should explain the methodology used and provide sufficient information for the financial analysis to be understood.

Depending on the circumstances, the report may address:

The Instructions

The report may identify the questions the expert has been asked to consider.

The Evidence Reviewed

Relevant financial and other documentation may be identified so that the basis of the analysis is clear.

The Methodology

The report may explain how the loss calculation has been approached and why particular financial information or assumptions have been used.

The Calculations

Relevant calculations may be presented with supporting schedules where appropriate.

Assumptions and Limitations

Material assumptions and limitations in the available evidence should be identified rather than left implicit.

Conclusions

The expert may provide conclusions on the accounting and financial issues that fall within the scope of their instructions.

For further information about the site's approach to financial damages and lost profits, see the Damages Quantification service.

Factors That Can Affect a Loss of Profits Calculation

Several factors can affect the outcome of a financial analysis, including:

• The quality and completeness of the underlying records
• The length of the relevant trading history
• The availability of reliable forecasts
• Changes in market conditions
• Changes in customer behaviour
• The complexity of the business
• The level of uncertainty surrounding the hypothetical scenario
• The assumptions used in the calculation

A calculation based on limited historical information may involve greater uncertainty than one supported by more extensive contemporaneous records.

Material limitations should be identified so that assumptions are not presented as established financial facts.

Working With the Legal Team

Solicitors may instruct an accounting expert witness to address specific financial questions arising from a commercial dispute.

Clear instructions can help establish:

• The issues requiring expert analysis
• The relevant period
• The financial information to be considered
• The assumptions that need to be examined
• Any alternative scenarios requiring analysis

An accounting expert's role remains distinct from that of the legal team. Legal questions and financial questions may overlap in a dispute, but an expert should address matters within their professional expertise and the scope of their instructions.

For information about providing a case brief, relevant financial records, key dates, and the questions requiring expert analysis, solicitors can review the Engage an Expert page.

Conclusion

Quantifying loss of profits in a commercial claim can require more than comparing revenue figures before and after an alleged event. An accounting expert witness may need to examine historical trading performance, potential revenue, profit margins, relevant costs, financial assumptions, alternative scenarios, and possible overlaps between claimed losses.

The appropriate methodology depends on the facts of the particular dispute and the evidence available. A clear distinction between established financial information, assumptions, and professional opinion can help ensure that the financial analysis is presented in a transparent and appropriately qualified manner.

The analysis of financial loss does not, by itself, determine the legal outcome of a commercial claim. The relevant legal issues remain matters for the court or tribunal and the parties' legal representatives.

For general enquiries about accounting expert witness services, see the Contact page.

Disclaimer: This article provides general information about the potential role of an accounting expert witness in loss of profits disputes. It is not legal, accounting, or financial advice and should not be treated as a substitute for advice specific to a particular case.

Last Reviewed: September 2026