Accountant negligence claims: examples and how PI responds

Reviewed by Apex Insurance Brokers · Last reviewed 2026-08-05

Even careful, competent accountancy firms face complaints. A client who suffers a financial loss and points to your advice or work as the cause can bring a claim in negligence or breach of contract. The claim does not have to be justified to cost you money — defending an unfounded allegation still consumes fees and time. This page sets out realistic, anonymised examples of the kinds of claims accountants face and explains, step by step, how professional indemnity insurance responds to each.

What counts as accountant negligence?

In broad terms, negligence arises where you owe a client a duty of care, you fall below the standard reasonably expected of a competent accountant, and that failing causes the client a foreseeable financial loss. The duty can be owed under your engagement contract and, in some circumstances, in tort. Bodies such as the ICAEW and ACCA set professional standards that a court may treat as evidence of what "reasonable competence" looks like.

Not every mistake is negligence, and not every unhappy client has a valid claim. But the cost of establishing that — through correspondence, expert evidence and sometimes litigation — is exactly what PI insurance is designed to absorb.

Anonymised examples and how PI responds

The scenarios below are illustrative composites, not real firms or cases. They show the typical shape of a claim and where the policy engages.

1. The missed tax filing deadline

A small practice files a client's corporation tax return late after an internal handover goes wrong. HMRC issues penalties and interest, and the client demands the firm reimburse the charges plus their own management time. Here PI typically responds to the client's claim for the penalties and interest that flow directly from the missed deadline, and covers the cost of negotiating or defending the amount claimed. Regulatory fines levied against the accountant personally are treated differently and are usually excluded — the cover is for the client's civil loss, not the practitioner's own penalties.

2. The incorrect tax advice

An accountant advises a client that a particular transaction will attract a certain tax treatment. HMRC later disagrees, the client faces an unexpected liability, and argues the advice was wrong and cost them money. PI responds by funding the defence — including tax counsel where needed to argue the advice was reasonable — and by meeting any settlement or award representing the client's genuine additional loss. Note that tax the client always lawfully owed is not itself a "loss"; the recoverable element is usually the extra cost caused by the negligent advice, such as penalties, interest or a lost mitigation opportunity.

3. The accounts error that misleads a decision

A firm prepares management accounts containing a material error. Relying on them, the client proceeds with an acquisition or a borrowing that they say they would have avoided had the figures been right. The alleged loss can be substantial and far exceeds the fee earned for the work. PI responds up to the policy limit; this scenario shows why the sum insured must reflect the size of decisions your figures inform, not the size of your invoices.

4. The audit or assurance oversight

An assurance engagement fails to pick up a material misstatement, and a third party who relied on the report claims they were misled. Third-party claims are common in accountancy because parties beyond your direct client — lenders, investors, buyers — may rely on your output. A well-drafted PI policy can respond to third-party claims, but the extent of any duty owed beyond the client is fact-specific and is exactly what the insurer's appointed defence tests.

5. The unfounded complaint

Sometimes a client simply blames the accountant for a loss the firm did not cause. The allegation is wrong — but rebutting it still means legal advice, correspondence and possibly a defended claim. PI pays these defence costs even where the firm is ultimately found not liable, which is often the most valuable feature of the cover for a small practice.

What a PI policy pays — and what it does not

Understanding the mechanics matters, because clients often assume "insured" means "everything is covered". It does not. Here is how a typical accountants' PI policy allocates cost:

Two features deserve emphasis. First, most PI policies are written on a claims-made basis: what matters is that the claim is made and notified during the current policy period, not when the work was done. This is why continuous cover — and run-off cover if you cease trading — is essential. Second, the limit of indemnity can be structured as "costs in addition to" or "costs inclusive of" the limit; the former protects your damages limit from being eroded by defence spend, and is generally preferable.

Notify early — it is a condition, not a courtesy

Perhaps the single most important thing an accountant can do to protect their cover is to notify the insurer as soon as they become aware of a claim or of circumstances that might give rise to one. A stroppy email, a hint of a dispute, a discovered error — these can all be notifiable circumstances. Late notification can prejudice or even void a claim. When in doubt, tell your broker; over-notifying is far safer than staying quiet. If you are reviewing your arrangements, you can request an accountants' PI quote here and check your notification terms at the same time.

Choosing an appropriate limit

Illustrative limits of £1m, £2m or £5m are common starting points, but the right figure depends on the value of the transactions and decisions your work influences, your fee income, contractual requirements from clients, and any minimum set by your professional body. A practice advising on large acquisitions or complex tax structures carries very different exposure from one doing straightforward compliance work. Discuss the aggregate limit, the number of reinstatements, and whether the limit is eroded by costs before you settle on a number.

Common questions

Does PI cover me if the client's claim turns out to be baseless?

Yes. One of the most valuable features of PI is that it funds your legal defence even when you are ultimately found not liable. You still pay your excess, but the cost of proving the allegation wrong is met by the policy.

Will PI pay a client's tax bill?

Not the tax the client always lawfully owed — that is not a loss caused by you. What PI can respond to is the additional, avoidable cost your negligence caused, such as penalties, interest, or a genuinely lost opportunity to mitigate. The insurer and its lawyers assess what element is truly recoverable.

I have retired but did the work years ago — am I still exposed?

Because PI is usually claims-made, a claim brought after you stop trading needs run-off cover in place at the time the claim is made. Without it, a policy that has lapsed will not respond, even though it covered you when the work was done.

Apex Insurance Brokers Limited is authorised and regulated by the Financial Conduct Authority (FRN 724952). This guide is general information, not advice on a specific policy or a substitute for your policy wording.