How much PI insurance cover do I need as an accountant in the UK?

~3 min read

Reviewed by Matthew Bartlett, Director · Last reviewed 2026-07-08

For accountants regulated by the Institute of Chartered Accountants in England and Wales, the answer is largely formulaic. The ICAEW Professional Indemnity Insurance Regulations, made under Bye-law 61, require every firm in public practice to hold a minimum limit of indemnity of at least the greater of £1.5 million or 2.5 times gross fee income for the last completed financial year, subject to a stated ceiling. That formula is the compulsory floor. Whether it's the right limit for your firm is a separate question. This entry sets out how the formula works, when to size above it, and where the ACCA, CIOT and ATT variations sit.

Short answer — market ranges

Sole practitioner or micro firm (≤£300k fees): £1.5m floor applies — 2.5× would produce a lower figure. Most placements sit at £1.5m.
Small firm (£300k–£800k fees): 2.5× gives £750k to £2m. Operative minimum is the £1.5m floor for firms up to £600k fees, then 2.5× above.
Mid-market firm (£1m–£3m fees): £2.5m to £7.5m compulsory floor. Broker recommendations often push into £5m–£10m depending on client concentration and audit exposure.
Larger firm (£3m–£10m fees): £7.5m to £25m compulsory floor. Firms with FTSE-listed audit clients or complex tax advisory typically layer top-up cover to £25m–£50m.
Above the ceiling: The Regulations cap the compulsory minimum. Above that, firms size to actual exposure, which for audit-heavy firms with material listed-client work runs well into eight or nine figures.

What counts as gross fee income

The Regulations use "gross fee income" to mean fees from all public practice work — audit, assurance, tax, accountancy, insolvency, corporate finance advisory, tax investigation, valuation, expert witness — done as an ICAEW member firm. Referral fees typically count. Disbursements passed through at cost do not. VAT is stripped. Where a firm operates alongside an unregulated subsidiary, only the ICAEW-regulated entity's fees are captured. Firms that have restructured, taken on lateral partners, absorbed another practice, or shed a service line during the year should recalculate carefully.

Where the formula floor is not enough

The 2.5× formula addresses average exposure across a book. It does not address peak exposure. Three scenarios where sizing well above the compulsory minimum is warranted.

Concentrated client exposure. A tax practice with three FTSE-listed clients earning £900,000 in aggregate fees carries a compulsory minimum of £2.25m — but a single mis-advised group reorganisation on any one of those clients could generate a claim well into eight figures. Peak-exposure sizing here should reflect the largest individual client's potential claim quantum, not the average.

Audit exposure. Statutory audit claims have a specific severity profile — they typically involve insolvency proceedings that crystallise years after the audit, and the quantum is driven by the value of the audited entity rather than the audit fee. Firms with material listed-audit exposure typically carry limits significantly above the 2.5× formula.

Insolvency practitioner exposure. Firms with IPs holding office face specific PI exposure that sits alongside the accountant PI regime. Recognised professional bodies (IPA, ICAEW, ACCA) apply their own insolvency PI rules on top of the accountancy body rules. Sizing needs to reflect both.

ACCA, CIOT, ATT variations

Members of the Association of Chartered Certified Accountants operate under a parallel regime — ACCA's Global Practising Regulations use a similar formula-driven scaling but with different band boundaries. Chartered Institute of Taxation and Association of Taxation Technicians members operate under adequacy standards rather than fixed formulae. Where a firm has members from more than one body, the operative minimum is the higher of the applicable calculations.

Client contract requirements

Public-sector engagements, framework agreements, and larger private-sector commercial appointments frequently specify minimum PII cover as a precondition. A firm's PII limit needs to satisfy the highest of the client contract requirements across the current book, not just the ICAEW minimum.

Worked example

Illustrative only. A four-partner ICAEW firm, £2.4m fees, mixed audit and tax. Compulsory minimum under 2.5×: £6m. Largest single audit client: FTSE 250 subsidiary. Realistic single-loss exposure: £15-25m on a materially mis-audited set of accounts. Broker recommendation: £10m primary layer plus £15m top-up for a £25m tower. Aggregation reviewed against the specific audit client cohort. Six-year run-off costed (though ICAEW's run-off floor is two years).

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