The Architects Registration Board publishes its annual PI declaration requirement, and most registered architects sign it once a year, attach the latest certificate of insurance, and move on. The declaration is short. The detail behind it — what ARB actually requires the policy to cover, how much, on what terms, and what happens when the wording falls short — is not.
This article unpacks the ARB Professional Indemnity Insurance criteria as they stand in 2026, with reference to the published criteria and to the way the architects' PI market in the UK has responded to them. It is written for sole-practitioner architects, partners at small and mid-sized practices, and principals at design-and-build firms with architectural capability. We assume you are familiar with the existence of PI cover but want to understand what the ARB framework actually does and does not require.
For the broader picture of architects' PI in the UK — claim patterns, market conditions, run-off, choosing cover — see the Architects PI Insurance UK Guide 2026.
What ARB requires, in summary
ARB's Standards of Conduct and Practice (Standard 8 in particular) requires that architects "have adequate and appropriate insurance cover for you, your practice and your employees". ARB then publishes detailed Professional Indemnity Insurance criteria setting out what "adequate and appropriate" actually means in practice. The criteria are reviewed periodically; the version current at the time of writing applies to all UK-registered architects practising in their own right or as principals of architectural practices.
The core elements:
Minimum levels of cover are set by reference to fee income. ARB's published position is that no architect should accept cover below £250,000 for each and every claim. The fee-income bands applied across the market follow this structure: practices with annual fee income up to £100,000 carry a minimum of £250,000 per claim; practices with fee income between £100,000 and £200,000 carry £500,000; practices with fee income above £200,000 carry £1m. These are per-claim minima — what the policy must respond to on any single notified claim.
Cover must be on a civil liability basis and on an each-and-every-claim basis with no aggregate cap. ARB's criteria require full civil liability cover (not the narrower "negligence, error or omission" basis), written so that the limit applies to each and every claim rather than being capped in the aggregate across the policy year.
Cover must be available retrospectively for past work. Architects' PI is written on a claims-made basis, meaning the policy in force when the claim is notified responds to the alleged work, regardless of when the work was actually done. The retroactive date on the policy should extend back to cover the architect's historic work. ARB has acknowledged the difficulty architects have faced obtaining retrospective cover for some historic exposures, and following its 2022 review it is no longer automatically misconduct where an architect, despite reasonable efforts, cannot obtain such cover.
Run-off cover must be available for past work after the architect ceases to practise. ARB recommends six years of run-off as a minimum, aligning with the standard contractual limitation period under English law (twelve years for deeds, which is the basis of most building contracts — more on this below).
The policy must be placed with a reputable insurer. ARB does not publish a list of acceptable insurers in the way ICAEW does for accountants. Architects rely on their broker to confirm that the insurer is appropriately regulated and rated.
The policy must not contain exclusions that would materially undermine the cover. ARB's criteria require that policies cover the architect's typical activities including design, contract administration, certification, project management and consultancy on architectural matters.
Excess is not capped by ARB. Unlike the SRA's solicitors' framework where excess is regulator-capped, ARB leaves the excess level to the architect and the insurer. Practices typically carry between £2,500 and £25,000, depending on practice size and risk appetite.
How the fee-income bands actually work in practice
The bands are based on gross professional fee income for the most recent accounting year, including subcontracted-out work where the practice carries the engagement risk. Practices that grow through a band threshold need to notify their insurer at renewal and may need to step up cover. Practices that contract below a threshold can in principle step down, but in practice most do not because the cost of additional cover above the minimum is usually modest and the protective value is real.
The lowest band — £250,000 minimum cover for practices under £100,000 fee income — applies to the bulk of UK sole-practitioner architects. Most carry exactly this minimum because the regulator allows it and because the practice's commercial work doesn't generate the cash flow to fund higher cover. The risk profile of these practices, in PI terms, is that the £250,000 limit can be inadequate to a serious claim on a substantial residential extension or a small commercial project; a claim that runs to £400,000 leaves the architect personally exposed for the difference.
The middle band — £500,000 cover for £100,000 to £200,000 fee income — covers many established small practices doing residential and small-commercial work. Many practices in this band buy at £1m rather than £500,000 because the marginal cost is small and the upside on the worst-case claim is significant.
The upper band — £1m cover for practices above £200,000 fee income — is the minimum for mid-sized practices. Practices doing larger commercial, public-sector or design-and-build work typically buy at £2m, £5m or more. The cost of upper-layer cover for architects has historically been higher than for accountants of similar size because architects' claim severities can be larger; a defective design on a substantial building can produce a multi-million-pound remedial cost.
What "any one claim" and "aggregate" mean in this context
Architects' PI is written as "any one claim" — the per-claim figure is the most the insurer will pay on a single notified claim. Importantly, ARB's criteria require that the cover is not subject to an aggregate limit, so the policy should respond afresh to each and every claim rather than being capped across the policy year. This is a meaningful protection: an architect can in principle face several separate claims in a year without the cover being exhausted.
Where an insurer offers a wording that does impose an aggregate cap — sometimes seen on certain extensions or for specific risk types such as fire safety or cladding — the architect and broker should check that the core cover still meets ARB's each-and-every-claim expectation. For mid-sized practices this matters because a single underlying design failure could plausibly produce multiple claims if it affected several projects.
Retroactive cover — the trap of changing insurer
Claims-made PI policies have a retroactive date — the earliest date back to which the policy will respond. When you change insurer, the new policy may have a retroactive date that falls short of your previous policy's, leaving a gap.
If you have been continuously insured by the same insurer for ten years and switch, the new insurer should issue a policy with a retroactive date going back at least ten years (in practice the new policy usually has "unlimited" or "full" retro). If the new insurer issues with a more restrictive retroactive date — say, three years — you have lost cover for past work between three years ago and ten years ago. Any claim notified now that relates to that older work will not respond.
ARB's criteria require that retroactive cover exists for all of the architect's past work. In practice this means architects who switch insurers should insist on full retroactive cover. A broker placing the renewal should be explicit about the retroactive date being offered.
Run-off, similarly, must be from a retroactive date covering the architect's past work — not from the date of ceasing practice.
Run-off — six years, twelve years, or longer
ARB recommends a minimum of six years' run-off cover after the architect ceases to practise. The basis for six years is the contractual limitation period under English law for ordinary contracts.
The complication is that most building contracts in the UK are executed as deeds, which extends the limitation period from six to twelve years. An architect who signed a deed of appointment on a project in 2020 and ceases practice in 2026 with six years of run-off cover is covered to 2032 — at which point the deed's twelve-year limitation period would not yet have run. The 2020 project's potential for late-notified claims extends to 2032 — six years of run-off is the bare minimum.
Practical advice for architects considering retirement, practice closure or career change: look at the longest-running engagement on your file (the project with the latest contractually-relevant date), identify whether it was executed as a deed, and structure run-off to cover the longer of six years from ceasing or the residual limitation period on the longest deed.
Run-off premium is normally paid up-front for the run-off period. Pricing varies but typically lands at 100% to 250% of the last working policy premium, paid as a single sum for the full run-off term. Some insurers offer staged run-off, paid annually; others want the lump-sum commitment.
Common policy wording variations to read carefully
Even within ARB's minimum framework, policy wordings vary. Watch for:
Design-and-build exclusions or sub-limits. Some standard architect policies exclude or sub-limit cover for design work where the architect is engaged by a contractor rather than directly by the client. If your practice does design-and-build work, the policy schedule needs to address it explicitly. We cover this in detail in our design-and-build risk article.
Building-type or use-type exclusions. Some policies exclude or sub-limit cover for specific building types — high-rise residential, particular types of cladding system, certain industrial uses. Post-Grenfell, high-rise residential and cladding-related work has been treated cautiously by insurers and some policies still carry restrictions.
Project-value sub-limits. Smaller-practice policies sometimes apply a sub-limit when the architect's work relates to a project above a defined construction value. If you have moved into larger projects, check whether your policy's sub-limit has been adjusted.
Contractor's liability extensions. If you act as Principal Designer under the CDM Regulations, ensure the policy covers your CDM duties as a defined activity.
Fitness-for-purpose exclusions. Most policies exclude liability assumed by the architect for "fitness for purpose" of the design — a stricter standard than the common-law duty of reasonable skill and care. If your appointment letter accepts a fitness-for-purpose obligation (some client appointment templates do), the architect is uninsured for that exposure even with full PI cover.
Performance guarantee exclusions. Similarly, undertakings to guarantee specific performance outcomes are usually outside PI cover.
What ARB monitoring actually checks
ARB's annual declaration requires the architect to confirm that PI cover is in place that meets the published criteria. ARB does not routinely review the policy wording itself; it accepts the architect's declaration in good faith. Where ARB investigates a complaint that may involve PI cover (typically following a serious project failure or a claim that the architect has paid out personally because their cover did not respond), ARB will then ask for the policy and may take regulatory action if the cover was materially deficient.
The practical implication is that architects can declare cover that does not in fact meet the criteria, and the issue only surfaces when something goes wrong. The work of placing cover that does meet the criteria — full retroactive, appropriate limit for the work being done, no material exclusions — sits with the architect and the broker.
How Apex helps
Apex acts as a PI broker for architectural practices in this profile range — from sole practitioners up to mid-sized regional practices. We work through the ARB criteria with the practice annually at renewal, confirm that the policy being offered meets the criteria in full (including retroactive date and any sub-limit or exclusion that would compromise the architect's regulatory position), and document the renewal decision.
We are independent and FCA-authorised; we do not have a quota with any insurer that would skew our recommendation. The Architects PI Insurance UK Guide 2026 is the full sector guide; the architects sector page and contact page are the places to start a renewal conversation.