An any one claim (or each and every claim) limit is available in full for every separate claim made in the policy year, while an aggregate limit is the most the insurer will pay for all claims in that year combined. ICAEW accepts either basis for its minimum cover, ACCA requires each and every claim cover except for high risk exposures, and some regulated work, such as ICAEW accredited probate work, must be insured on an any one claim basis.
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What is the difference between the two?
The ICAEW PII Regulations define the terms in their glossary of policy language. The aggregate is the total amount of indemnity available in a particular policy year (paragraph 6.34). An each and every claim limit, which may also be written as any one claim, is available to meet each claim; there is no overall limit on the number of claims, and multiple claims could each be paid up to the limit (paragraph 6.36). ACCA’s guidance factsheet notes that aggregate cover may also be described as “any one claim and in all” or “each and every claim and in the aggregate”, which is why the full schedule wording needs reading and not just the first few words.
Because PII is written on a claims made basis, the limit that counts is the one in the policy year when the claim is first made or the circumstance first notified. Every claim made in that year draws on the same aggregate, whichever year the work was done in.
What does ICAEW require?
Regulation 3.2 of the ICAEW PII Regulations effective from 1 October 2026 sets a minimum limit in each policy year of at least £2 million for any single claim and in the aggregate. The guidance explains that a firm may buy £2 million in total to cover all claims in the year, or £2 million on an each and every claim basis, which could provide more cover in total if several claims are made. The qualifying insurance up to £2 million must be with a participating insurer on an aggregate or each and every claim basis; above that limit, cover need not be with a participating insurer or on the approved minimum wording.
Under regulation 3.3, a firm with gross fee income of less than £800,000 must have a minimum limit, again for any single claim and in the aggregate, of two and a half times its gross fee income, with a minimum of £250,000. ICAEW adds that these firms should always consider whether cover below £2 million is enough or whether a higher limit or cover on an any one claim basis is more appropriate, and paragraph 6.14 reminds all firms that the £2 million minimum may not be adequate.
Two kinds of work change the picture:
- Probate and estate administration. Under regulation 3.5, an accredited legal services firm needs at least £500,000 for any one claim for authorised work. ICAEW’s guidance says that if the firm’s main policy is aggregate, it must either move to an each and every claim basis or obtain an extension of cover for that work.
- Insurance distribution. Under regulation 3.4, firms licensed under the Designated Professional Body arrangements or authorised by the FCA for insurance distribution must meet the limits the FCA prescribes for that activity. ACCA’s March 2025 article on PII for regulated work puts these at €1,250,000 per claim and €1,850,000 in the aggregate.
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What does ACCA require?
ACCA’s Global Practising Regulations (GPR 9(3)) require cover for each and every claim. Its factsheet says ACCA continues to require each and every claim cover, as opposed to each and every claim and in the aggregate, because this is in the consumer interest. The minimum limits are:
| Firm’s total income | Minimum each and every claim limit |
|---|---|
| Less than £600,000 | The greater of two and a half times relevant total income and £100,000 |
| £600,000 or more | £1.5 million |
GPR 9(3)(b) allows an aggregate basis for high risk exposures if that is all insurers will offer. ACCA gives cyber related events, tax planning and financial services as examples, and a firm does not need to apply for a waiver for these. ACCA’s practical advice is that, ideally, the limit should be any one claim with defence costs in addition, and members should watch for providers offering aggregate or defence costs inclusive cover.
What about AAT and other regulators?
AAT requires licensed members to hold cover of at least the greater of two and a half times gross fee income and £50,000 for sole traders, or £100,000 for partnerships and limited companies, with a maximum required level of £1,000,000 where gross fee income exceeds £400,000. Its published requirements also call for full civil liability cover and full retroactive cover, so members should confirm the claims basis directly with their insurer or broker.
Other regulators set their own terms. ACCA’s 2025 article notes that ACCA members authorised for probate through CILEX need a minimum of £2 million any one claim, excluding defence costs, and that CAA ATOL reporting accountants need cover at least equal to the CAA liability cap, which ranges from £250,000 to £20,000,000. A firm doing several kinds of regulated work needs a policy, or a combination of policies, that satisfies every requirement at once. The general principles are covered in professional indemnity insurance for accountants and in the overview of insurance an accountancy practice needs.
How do defence costs and the excess interact with the basis?
Under clause C1.2 of the ICAEW minimum approved wording, the limit of indemnity is exclusive of defence costs, which are paid in addition. If a claim settles for more than the limit, the insurer pays only the proportion of defence costs that the limit bears to the total settlement. A defence costs inclusive aggregate policy is the weakest combination: legal fees on one claim reduce what is left for damages on that claim and on every other claim that year.
Excess works the other way. Regulation 3.7 lets an ICAEW qualifying policy include an aggregate excess no higher than the greater of £3,000 and 3% of gross fee income, so once the firm has paid that much in excesses in a year it pays no more. Clause C3.2 of the wording stops the excess applying to defence costs, except for claims from FCA authorised work. ACCA instead restricts the uninsured excess to £20,000 per principal for each and every claim.
When does an aggregate limit become a real risk?
An aggregate limit works well while claims are rare and small. It becomes a problem when one year brings several claims, which is more likely than it sounds:
- the same advice or planning structure was used for many clients and HMRC challenges it;
- a systemic software or process error affects a whole batch of returns;
- a departing partner’s files are reviewed and several historic problems are notified together;
- a large claim uses most of the limit, leaving little for anything else that year.
Firms doing tax planning, corporate finance or work for high value clients are most exposed, which is why ACCA lists tax planning among the high risk exposures insurers may only offer on an aggregate basis. The page on PI claims arising from tax advice explains how these claims typically arise.
How might the two bases compare?
Illustration only. An ICAEW firm with gross fee income of £1 million needs at least £2 million under regulation 3.2. It chooses between £2 million in the aggregate and £2 million any one claim, both with defence costs in addition.
In one policy year two clients bring claims, settled at £1.5 million and £1.2 million. On the aggregate policy, the insurer pays £1.5 million on the first and only £500,000 on the second, leaving the firm and its principals to find £700,000. On the any one claim policy both claims are within the limit and are paid in full, less the excess. The premium difference between the two options is the price of that protection.
What mistakes do firms make?
- Reading only the headline limit and missing the words “in the aggregate” or “costs inclusive” on the schedule.
- Assuming that meeting the regulatory minimum means the cover is adequate; ICAEW and ACCA both say it may not be.
- Taking on probate, insurance distribution or other regulated work without checking that the main policy meets its separate basis and limit.
- Capping liability in engagement letters at a figure that relies on an aggregate limit which may already be used up; see limiting liability in engagement letters.
- Cutting the limit as fee income falls, when ICAEW advises against reducing cover until completed accounts show the fall, because claims arise from earlier, busier years.
Solar Protect runs fee protection schemes for accountancy and bookkeeping practices. See how our accountant schemes work or read fee protection schemes for accountants.
Related Accountapedia entries
- Minimum professional indemnity insurance for accountants
- AAT, ACCA or ICAEW: which body for your practice
- PI insurance when buying or merging practices
- Run off cover when an accountant retires
- Starting an accountancy practice
Sources
- ICAEW: Pii regulations effective 1 october 2026
- ACCA: Professional indemnity insurance requirements
- ACCA: PII limits for regulated work
- ACCA: PII
- AAT: Pii
- ICAEW: Pii minimum approved policy effective 1 september 2021
Reviewed by Christine Anderson, Broker, Solar Protect. Last reviewed 19 October 2026. Part of Accountapedia, the Solar Protect guide to UK tax and accounting. This page is general information, not personalised advice.