Business Interruption Insurance — UK Guide for SMEs

Business interruption (BI) insurance covers the financial loss your business suffers when it cannot trade normally following an insured event. It is one of the most misunderstood and most frequently underinsured commercial policies — yet it can be the difference between a business surviving or closing permanently after a major disruption. The COVID-19 pandemic brought BI cover into sharp focus, prompting a landmark Supreme Court ruling that reshaped how policies are interpreted.

1. What Business Interruption Insurance Covers

Business interruption insurance does not pay for the physical damage to your property — that is the role of your buildings and contents insurance. BI cover pays for the financial consequences of being unable to trade, including:

• Lost gross profit — the turnover (net of specified variable costs) you would have generated during the period your business was affected
• Fixed costs — ongoing expenses that continue even when you are not generating revenue: rent, loan repayments, utility standing charges, and salaries of essential retained staff
• Increased cost of working — additional expenditure you incur specifically to keep trading or to speed up recovery, such as hiring temporary premises, using couriers instead of your own delivery vehicles, or overtime payments. These costs are only covered to the extent they reduce the business interruption loss

The aim is to put you in the same financial position as if the insured event had not occurred — no better, no worse. The cover period runs from the date of the insured event until you have returned to normal trading levels, subject to the maximum indemnity period selected.

2. Key Triggers

BI insurance is not a standalone policy — it is almost always linked to a material damage policy (buildings, contents, or stock insurance). The principal triggers are:

• Property damage — fire, flood, storm, burst pipes, theft, or vandalism causing physical damage that forces closure or restricts operations
• Equipment breakdown — failure of key machinery, refrigeration, or IT systems (often covered under a separate machinery breakdown extension)
• Denial of access — a competent public authority prevents access to your premises following a nearby incident (e.g. a gas leak or structural collapse of an adjacent building) even if your own property is undamaged
• Loss of access due to damage — access to your premises is blocked because of damage to nearby property or public utilities

Extensions can also provide cover for suppliers, customers, utilities failure, infectious disease, and public authority action — see section 5.

3. Indemnity Period

The indemnity period is the maximum number of months for which your insurer will pay a BI claim following an insured event. Standard options are 12, 24, or 36 months.

Why 12 months is often not enough:

• Rebuilding or repairing commercial premises after a major fire or flood typically takes 12–18 months, plus time to obtain planning permission and building control sign-off
• Replacing specialist or bespoke manufacturing equipment may take many months for delivery, installation, and commissioning
• After a long closure, rebuilding your customer base and revenue to pre-loss levels takes additional time beyond reopening
• If key staff leave during an extended closure, recruiting and training replacements extends the recovery period further

The premium difference between a 12-month and 24-month indemnity period is typically modest relative to the risk. Insurance professionals almost universally recommend a minimum of 24 months for SMEs; those in sectors with complex supply chains, long lead times for equipment, or regulated environments may need 36 months.

4. Sum Insured — Gross Profit Calculation

Underinsurance is the most common BI claim problem. The sum insured must represent the gross profit your business would have generated over the entire indemnity period.

For a 12-month policy the sum insured should broadly equal:

• Turnover (projected for the next 12 months) minus uninsured working expenses (variable costs that would cease if the business stopped trading — typically raw materials, bought-in goods, and packaging, but NOT wages, rent, or other fixed costs)

For a 24-month indemnity period, the sum insured should cover two years of projected gross profit. Many businesses make the mistake of using the gross profit figure from their accounts, which deducts labour costs and other fixed costs, resulting in significant underinsurance. If you are underinsured, the insurer may apply average (proportional reduction) to your claim payout.

Review your sum insured every year and whenever your business changes materially — a new contract, a price increase, or a change in product mix can all affect the correct figure.

5. Extensions

Standard BI policies triggered solely by damage to your own premises may leave significant gaps. Common extensions include:

• Suppliers extension— covers loss of income following damage to or disruption at a named supplier's premises
• Customers extension— covers loss of revenue where a key customer's premises are damaged and orders to you are reduced or cancelled
• Utilities failure— covers interruption caused by failure of mains gas, electricity, water, or telecommunications due to damage at the utility provider's infrastructure
• Infectious disease — covers business closure ordered by a public authority following an outbreak of a specified notifiable disease at or near the premises
• Public authority (denial of access) — extends cover where a competent authority prevents access to your premises even if your own property is undamaged
• Contingency — covers cancellation of events or contracts beyond your control

Each extension has its own trigger wording — read carefully and ask your broker to explain exactly what circumstances would or would not be covered.

6. COVID-19 Lessons — the FCA Test Case

The COVID-19 pandemic generated the largest volume of contested BI claims in UK insurance history. When businesses were forced to close in March 2020, many found that their insurers denied claims on the basis that the policy only covered BI flowing from physical damage to the insured's own premises.

The FCA brought a test casein the High Court in 2020, which was appealed to the Supreme Court. The Supreme Court's judgment in January 2021 found in favour of policyholders in many (but not all) situations:

• Disease clauses — where policies covered BI following the occurrence of a notifiable disease within a specified radius of the premises, the UK-wide spread of COVID-19 was found sufficient to trigger the clause, as COVID-19 was present everywhere, including within any specified radius
• Denial of access clauses — where policies covered loss of access due to action by a public authority, government closure orders triggered many such clauses
• However, policies that required physical damage to the insured premises as a prerequisite were generally not triggered by COVID-19

Key lessons: policy wording matters enormously. Two businesses with nominally similar BI cover from different insurers could have entirely different outcomes. Always read (or have your broker read) the specific trigger wording, any exclusions for communicable disease, and the conditions precedent to notification.

7. How to Calculate Gross Profit for BI Insurance

The insurance definition of gross profit differs from both the accounting definition and the HMRC definition. For most BI policies, gross profit means:

Gross Profit (BI) = Turnover + Closing Stock − Opening Stock − Purchases/Bought-in Services

Or more simply: Turnover minus all variable (uninsured) costs

The specification of which costs are “uninsured working expenses” (and therefore deducted) varies between policies. Typical inclusions are:

• Raw materials and components
• Bought-in goods for resale
• Packaging materials
• Freight and carriage costs directly related to sales

Costs that are typically notdeducted (because they continue during a closure) include wages, rent, business rates, and insurance premiums themselves. Always calculate your gross profit sum insured using your specific policy's definition, not the figure from your management accounts.

8. Making a Claim

If an insured event occurs:

1. Notify your insurer or broker immediately — most policies require prompt notification; delay can prejudice your right to claim
2. Document everything — photograph and video all damage before any clean-up; retain damaged items for the loss adjuster to inspect
3. Keep detailed financial records — maintain a log of all additional costs incurred, and ensure your accounts clearly show the period of reduced income
4. Mitigate — take all reasonable steps to minimise the disruption and resume trading as quickly as possible; document what you did and why. Costs of mitigation (increased cost of working) are recoverable under the policy
5. Appoint a loss assessor — for significant claims, consider engaging an independent loss assessor (who acts for you, not the insurer) to help compile, present, and negotiate the claim. Their fee is often recoverable under the policy or negotiable with the insurer
6. Engage with the loss adjuster— the insurer will appoint a loss adjuster (who acts for them) to investigate the claim; cooperate fully but understand that their role is to protect the insurer's interests

9. Common Exclusions

Be aware of typical policy exclusions:

• War and terrorism — terrorism cover is sometimes available as a separate extension or under Pool Re
• Cyber attacks — many standard BI policies now exclude cyber-related losses; check whether a separate cyber insurance policy is needed (and whether it includes business interruption)
• Deliberate acts by the insured — cover is voided if the loss is caused intentionally by the policyholder
• Wear and tear / gradual deterioration — slow deterioration of equipment or premises is not a sudden insured event
• Communicable disease exclusions — added by many insurers after COVID-19; check carefully whether your current policy excludes pandemics or notifiable diseases
• Pre-existing conditions — damage or issues known before the policy incepted

10. Choosing a Policy

When comparing BI policies:

• Indemnity period — select 24 or 36 months as a default for most businesses; review your specific recovery time risk
• Sum insured — calculate using the insurance definition of gross profit, projected over the full indemnity period; build in a margin for growth
• Extensions — consider which extensions are relevant to your business model (supplier dependency, key customers, infectious disease)
• Policy wording — compare the exact trigger clauses; do not assume that similar-sounding policies provide the same cover
• Use a specialist broker — a commercial insurance broker with experience in your sector will know which insurers offer the most comprehensive wordings and can negotiate on your behalf. Buying BI cover directly online without advice significantly increases the risk of underinsurance or gaps in cover

BI cover checklist