If you design buildings or advise on construction in the United Kingdom, the chances are that at least one professional body sets out a minimum standard for the professional indemnity (PI) insurance you must hold. For most architects and architectural technologists, that body is the Architects Registration Board (ARB), the Royal Institute of British Architects (RIBA), the Chartered Institute of Architectural Technologists (CIAT), or some combination of all three. The rules look similar at first glance — minimum cover, run-off, civil liability wording — but the calibration is different, and the differences matter when you are sizing a policy or planning a practice.
This guide compares the publicly available PI requirements of ARB, RIBA and CIAT as understood at the time of writing in May 2026. The positions referenced here are based on each body's published material and are subject to periodic review. Figures, thresholds and wording requirements can and do change, so practitioners should verify the current position directly with the relevant body before relying on any specific number when arranging or renewing cover.
What this comparison covers
The aim here is to set out, in neutral terms, what each of the three bodies requires of practitioners who fall within its scope, and to identify the dimensions on which their regimes differ. We compare minimum limit positions, aggregation, run-off, wording basis, the treatment of defence costs, and the way each regime interacts with fitness-to-practise and continuing professional development (CPD).
The comparison does not address every nuance of each body's rulebook, nor does it provide regulated advice on which limit or policy structure a specific practice should buy. It does not cover the design liabilities that flow from individual contracts (for example, collateral warranties, net contribution clauses, or fitness-for-purpose obligations imposed by clients), and it does not address the separate requirements that may apply under the Building Safety Act 2022 regime for higher-risk buildings. Where readers want a position on their own practice, the right step is to speak to a broker or to the relevant body's professional standards team.
Why the bodies set different requirements
The three bodies are not interchangeable, and their PI rules reflect different mandates.
The ARB is the statutory regulator of the architects' profession in the United Kingdom under the Architects Act 1997. Anyone using the title "architect" in business or practice must be on the ARB Register, and the ARB's Architects Code sets out the conduct standards that registrants must meet. PI insurance is one of those standards, so the ARB's position effectively sets a regulatory floor for individual registered architects.
The RIBA is a chartered membership body. It does not regulate the title "architect" — that is the ARB's role — but it does charter individual members and accredit Chartered Practices. The RIBA Code of Professional Conduct and its associated standards, including the PI Insurance Standard for Chartered Practices, apply to those who choose to be RIBA members or to hold Chartered Practice status. Because RIBA is positioning at the level of a chartered practice, its requirements typically sit at or above the statutory floor.
The CIAT is the professional body for architectural technologists. Its Code of Conduct applies to Chartered Architectural Technologists (MCIAT) and to firms registered under the Chartered Practice scheme. CIAT's PI requirements are scaled to the typical fee income of an architectural technology firm and reflect the scope of services such firms commonly provide.
In short: ARB sets a regulatory minimum tied to the protected title "architect"; RIBA layers a chartered standard on top for its members and practices; CIAT calibrates separately for architectural technology firms. None of these positions cancels the others out. A registered architect who is also a RIBA Chartered Member and runs a RIBA Chartered Practice will need to satisfy ARB and RIBA. A practice that has both architects and architectural technologists may need to satisfy all three.
Body 1: ARB — the statutory regulator's position
Who it applies to
The ARB's PI requirement applies to every individual on the Register of Architects who is in business or practice. The obligation rests on the individual architect, not on the firm. Where an architect is employed by a practice, the practice's policy can satisfy the requirement, but the architect remains personally responsible for confirming that adequate cover is in place.
Minimum cover position
As understood at the time of writing, the ARB requires registrants to hold PI insurance with a minimum limit of indemnity of GBP 250,000 for any one claim, with a higher minimum of GBP 500,000 applying to sole principals and partnerships whose turnover exceeds a published threshold. The ARB publishes the current threshold and the exact figures on its website and reviews them periodically. Practitioners should verify the current position with the ARB before treating any specific number as definitive.
The ARB is clear that GBP 250,000 is a floor, not a recommendation. Architects are expected to assess the cover they actually need based on the nature, scale and risk profile of the work they undertake, and to buy a limit consistent with that assessment.
Aggregation
The ARB's minimum is expressed on an each-and-every-claim basis. That means the limit should be available, in principle, for each separate claim made during the policy period, rather than being aggregated across all claims in the year. Some policies impose aggregation for specific categories of risk (for example, asbestos or fire safety) and architects should check that any such aggregation does not bring the limit below the ARB floor for the claims to which it applies.
Run-off
The ARB requires architects who cease to practise to maintain run-off cover for a period that aligns with the statutory limitation periods for negligence and breach of contract under English law. In practice this typically means at least six years for contract claims, with a longer tail for claims framed in tort under the Latent Damage Act 1986. The ARB's published guidance sets out its expectations for run-off in more detail and is the authoritative source.
Wording requirements
The ARB does not mandate a specific policy wording, but it expects cover to be written on a civil liability basis (which captures negligence, breach of contract and other civil claims arising from the practice of architecture) rather than on a narrower negligence-only basis. Defence costs should be included in addition to, or at least clearly within, the limit of indemnity in a way that does not erode the cover available for damages below the regulatory floor.
Critical compliance points
The most common ARB compliance issues seen in practice are unintended gaps at retirement (where run-off was not arranged in time), policies that aggregate certain claim types in a way that drops the available limit below the ARB minimum, and confusion about who the policy actually covers when an architect moves between firms. The ARB is explicit that the obligation sits with the individual architect, so a registrant cannot assume that an employer's policy is fit for purpose without checking.
Body 2: RIBA — the chartered practice standard
Who it applies to
The RIBA PI Insurance Standard applies to RIBA Chartered Practices. Individual RIBA members who are not principals of a Chartered Practice are still subject to the Code of Professional Conduct, which requires appropriate PI cover, but the detailed Standard with its sliding scale is directed at the practice level.
Minimum cover position
The RIBA PI Insurance Standard, as publicly available at the time of writing, sets minimum levels of cover on a sliding scale linked to the annual turnover of the Chartered Practice. The scale starts at a level above the ARB statutory floor for the smallest practices and rises in bands as turnover increases. The exact bands and figures are published by RIBA and are reviewed periodically. Practitioners should verify the current bands directly with RIBA before relying on any specific figure.
The Standard is framed as a minimum for Chartered Practice status. As with the ARB position, RIBA is clear that practices may need to buy more than the minimum depending on the projects they take on, the contracts they sign, and the contractual requirements imposed by clients (which on larger projects often specify a limit well above the Standard).
Aggregation
The RIBA Standard, as publicly available, contemplates cover on an each-and-every-claim basis, consistent with the way the ARB position is structured. Where aggregation applies to specific categories of claim (such as pollution, asbestos, or cladding-related risks), practices are expected to consider whether the aggregated sub-limit is sufficient for the work they undertake.
Run-off
The RIBA Standard contemplates run-off cover when a Chartered Practice ceases or restructures, again typically aligned with the six-year statutory limitation period for contract claims. RIBA's guidance acknowledges that practices may choose to buy a longer tail where their work creates exposure on a longer horizon, for example design work on buildings that fall within the Building Safety Act 2022 regime.
Wording requirements
RIBA expects cover to be written on a civil liability basis, with defence costs treated in a way that does not undermine the available limit. The Standard also addresses the treatment of any one claim and aggregate wordings, and sets expectations on the inclusion of certain extensions that are typical for architectural practice (for example, cover for collateral warranties given on standard terms).
Critical compliance points
For Chartered Practices the most common areas of attention at renewal are turnover-band slippage (where the practice has grown into a higher band and needs to step the limit up), management of project-specific PI requirements written into client contracts that sit above the Standard, and the practice's approach to risks subject to aggregated sub-limits.
Body 3: CIAT — the architectural technologists' regime
Who it applies to
CIAT's PI position applies to Chartered Architectural Technologists (MCIAT) who are in practice on their own account, and to firms registered under the CIAT Chartered Practice scheme. CIAT members who are employed by a firm whose policy meets the requirement are generally treated as covered through their employer.
Minimum cover position
CIAT's Chartered Practice scheme, as publicly available at the time of writing, requires PI cover scaled to the firm's annual fee income, with a minimum floor below which practices cannot fall. The scale is set out in CIAT's published Chartered Practice criteria and is reviewed periodically. The structure is conceptually similar to the RIBA approach — a floor for the smallest firms, rising in bands as fee income increases — but the bands and figures are calibrated for architectural technology firms and may differ from the RIBA numbers. Practitioners should verify the current figures directly with CIAT.
Aggregation
As with the other two regimes, CIAT contemplates cover on an each-and-every-claim basis as the standard structure. Aggregated sub-limits for specific risks should be considered against the type of work the firm undertakes.
Run-off
CIAT's Chartered Practice criteria address run-off cover for firms that cease to trade, again aligned with the statutory limitation horizon. CIAT's guidance recognises that some architectural technology services (for example, building surveys or technical due diligence) can give rise to claims emerging some years after the work was completed, so adequate run-off is treated as an integral part of the regime rather than an optional add-on.
Wording requirements
CIAT expects cover to be written on a civil liability basis and to include defence costs in a way that does not erode the limit below the floor required by the scheme. As with RIBA, certain extensions typical for architectural technology practice (for example, cover for design responsibility taken on under contractor-led procurement routes) are addressed in the published criteria.
Critical compliance points
The most common issues at renewal for CIAT Chartered Practices are fee-income-band slippage, mismatch between the scope of services actually offered and the activities described to insurers, and the treatment of design responsibility taken on through design-and-build sub-consultancy where the contractual chain can be long and the obligations onerous.
A summary table of the three regimes
The following table summarises the key dimensions of each body's regime, as understood at the time of writing. It is a simplified comparison and should not be relied on in place of the published rules of each body.
| Dimension | ARB | RIBA (Chartered Practice) | CIAT (Chartered Practice) | |---|---|---|---| | Type of body | Statutory regulator | Chartered membership body | Chartered membership body | | Who is covered | Individual registered architects | RIBA Chartered Practices and their members | MCIATs in practice and Chartered Practices | | Minimum limit | Floor (GBP 250,000 / GBP 500,000 depending on turnover threshold — verify current figures) | Sliding scale by turnover, set above the ARB floor at entry | Sliding scale by fee income, set at the level appropriate to architectural technology firms | | Aggregation | Each-and-every-claim basis | Each-and-every-claim basis | Each-and-every-claim basis | | Run-off | Required on ceasing practice; typically six years to align with statutory limitation | Required on ceasing or restructuring; six years typical, longer tails encouraged for longer-tail exposures | Required on ceasing practice; six years typical | | Wording basis | Civil liability | Civil liability | Civil liability | | Defence costs | Required, treated so as not to erode the regulatory floor | Required, treated so as not to undermine the Standard | Required, treated so as not to undermine the scheme floor | | CPD interplay | CPD is a separate Code obligation; PI failures can themselves be a Code issue | CPD required for Chartered Membership; PI is a separate Standard | CPD required for MCIAT; PI is part of Chartered Practice criteria |
Practitioners should treat this table as a starting point and check the current published rules of each body when arranging or renewing cover.
Dimensions worth comparing in more depth
Limit, floor and cap
All three regimes operate by setting a minimum (a floor) rather than a cap. None of them tells you that you cannot buy more, and none of them treats their published figure as a recommendation. The ARB floor is the lowest of the three because it has to work for every registered architect, including those at the smallest end of the profession. The RIBA Standard and the CIAT scheme are calibrated for chartered practices and reflect the typical risk profile of those populations.
Aggregation
The default position across all three is each-and-every-claim cover. Where a market hardens, insurers sometimes impose aggregated sub-limits for specific perils, and that can create a gap against the regulatory floor for claims that fall within the aggregated category. Practitioners should specifically check whether any aggregated sub-limit on their policy could bring the available cover below the floor required by the body or bodies that regulate them.
Run-off
All three bodies link their run-off expectations to the statutory limitation horizon. The Limitation Act 1980 gives six years for contract claims, twelve years where the contract is executed as a deed, and up to fifteen years from the negligent act under the Latent Damage Act 1986. Six years is the conventional minimum for run-off, but practices that have signed deeds or worked on long-tail building safety projects often consider longer tails.
Wording basis
The civil liability basis is the standard across all three regimes and is broader than a negligence-only wording. Civil liability covers negligence, breach of contract and breach of statutory duty, and is the wording PI insurers typically offer for design professionals in the United Kingdom.
Defence costs
Defence costs in PI policies can be structured in three broad ways: within the limit (so that defence costs erode the cover available for damages), in addition to the limit (so they sit on top of it), or as a separate costs-and-expenses limit. All three bodies expect the structure not to undermine the floor. In practice, an in-addition structure is the cleanest way to comply.
Fitness-to-practise and CPD interplay
PI insurance is not a substitute for fitness-to-practise or CPD obligations, but the bodies treat the existence and adequacy of PI cover as a fitness-to-practise matter in its own right. Failing to hold cover that meets the floor can itself be a Code or Standard breach, separate from any underlying claim. CPD obligations sit alongside this and are addressed in each body's separate framework.
What to ask before choosing your PI cover
A useful first step is to identify which bodies actually regulate or charter you, because that determines which floor or floors you have to clear. Once that is settled, the questions to work through include the limit you need (separately from any minimum), whether that limit is each-and-every-claim or aggregated, how aggregation interacts with any sub-limits that apply to specific risks, whether defence costs sit inside or outside the limit, the run-off position you would inherit if the practice ceased today, and the wording basis used by the policy. It is also worth checking whether any client contracts you have signed impose PI requirements above the body's floor — on larger projects this is common — and whether the policy you hold can actually evidence compliance to a client who asks for confirmation.
The checklist below sets out the questions in a form that can be taken into a renewal meeting:
- Which body or bodies regulate the practice, and what is the current published floor for each?
- Is the limit each-and-every-claim, and does it meet the highest applicable floor?
- Do any aggregated sub-limits drop the available cover below that floor for the risks they cover?
- Are defence costs in addition to the limit, or within it, and if within, is the structure compliant?
- What run-off would apply if the practice ceased trading at the next renewal, and for how long?
- Is the wording on a civil liability basis, and does it cover the full scope of services actually offered?
- Are there client contracts that impose higher PI requirements that need to be reflected in the limit bought?
A broker can work through these questions with the practice, but the underlying judgements — about scope of services, contractual obligations and project pipeline — have to be made by the practice itself.
When each body's regime suits which buyer
For the sole practitioner architect without Chartered Practice status, the ARB position is the operative regulatory floor, with the higher GBP 500,000 minimum kicking in above the published turnover threshold. The practical question for this buyer is usually whether the regulatory floor matches the limit actually needed, and the answer is often no — client contracts, project values and the practice's risk appetite typically push the bought limit above the floor.
For the small to medium RIBA Chartered Practice, the RIBA Standard is the operative regime and sits above the ARB floor by design. The sliding scale means that as the practice grows, the minimum steps up, and the renewal conversation each year should include a check on whether the practice has moved into a higher band.
For the architectural technology firm holding CIAT Chartered Practice status, the CIAT scheme is the operative regime, calibrated for the typical fee income and scope of services of architectural technology practices. Where the firm employs both architects and architectural technologists, the firm has to clear all the applicable floors, which in practice usually means meeting whichever is highest at any point on the scale.
None of these regimes is "better" than the others; they are differently calibrated for different populations, and a practice that falls within more than one has to satisfy each of them.
Frequently asked questions
Do I have to be regulated by all three of ARB, RIBA and CIAT?
No. ARB regulates the title "architect" and is mandatory for anyone using that title in practice. RIBA membership is voluntary, although it brings access to the Chartered Practice scheme. CIAT regulates Chartered Architectural Technologists and is the relevant body for that profession. Many practitioners are regulated by one body only; some by two; a smaller number by all three.
Is the ARB minimum the same as the RIBA minimum?
No. The ARB sets a statutory floor for individual architects and applies a higher figure above a turnover threshold. The RIBA Standard sets a sliding scale for Chartered Practices that starts above the ARB floor and steps up as turnover increases. The actual figures and bands are published by each body and reviewed periodically; practitioners should verify the current position before relying on any specific number.
What happens to run-off cover if I retire?
All three bodies expect run-off cover to be in place after a practitioner or practice ceases to trade. Six years is the conventional starting point because it aligns with the statutory limitation period for contract claims in England and Wales, but longer tails are sometimes considered where deeds have been signed or where work falls within the Building Safety Act 2022 regime. The specific expectations are set out in each body's published guidance.
My PI policy aggregates cover for fire safety claims. Does that comply with ARB?
Aggregation of specific claim types is common in the current market, particularly for risks such as cladding or fire safety. Whether the aggregated sub-limit complies with the ARB position depends on whether the available cover for any one claim still meets the ARB floor at the time the claim is made. The ARB's position is that the floor must be met on an each-and-every-claim basis, so a sub-limit that drops the available cover below the floor for the claims it applies to is likely to be a compliance issue. Practitioners with aggregated sub-limits on their policy should discuss the implications with their broker.
I am a RIBA Chartered Member but I am not a principal of a Chartered Practice — does the PI Standard apply to me?
The detailed PI Insurance Standard is directed at Chartered Practices. Individual Chartered Members who are not principals of a Chartered Practice are subject to the RIBA Code of Professional Conduct, which requires appropriate PI cover, but the sliding-scale Standard is not directly aimed at the individual member. The relevant floor for that member as an architect is the ARB position.
How does the CIAT scheme treat firms that have both architects and architectural technologists?
A firm that employs both architects and architectural technologists may need to satisfy the ARB position for its architects (carried through the firm's policy if structured that way), the RIBA Standard if it is a RIBA Chartered Practice, and the CIAT scheme if it is a CIAT Chartered Practice. In practice, this typically means the firm's policy needs to clear the highest applicable floor at any given band on the scale.
Are defence costs included in the regulatory minimum, or in addition to it?
The bodies expect defence costs to be structured so that they do not erode the available cover below the regulatory floor. The cleanest way of achieving this is to buy defence costs in addition to the limit of indemnity, although policies vary. The right answer depends on the wording offered by the insurer and on the floor that has to be met.
Where can I check the current ARB, RIBA and CIAT positions?
Each body publishes its current PI requirements on its own website and in its rulebook. The ARB publishes its position in the Architects Code and associated guidance, RIBA publishes the PI Insurance Standard for Chartered Practices, and CIAT publishes the Chartered Practice criteria. These positions are reviewed periodically. Practitioners should check the current published material before arranging or renewing cover.
About this guide
This guide was written by Apex Insurance Brokers Ltd, a UK insurance broker based in Bristol. Apex Insurance Brokers Ltd is authorised and regulated by the Financial Conduct Authority (firm reference 724952) and registered at Companies House under number 07014570. The guide was last reviewed in May 2026.
The positions described above reflect the publicly available rules of the ARB, RIBA and CIAT as understood at the time of writing. All three bodies review their rules periodically, and figures, bands, thresholds and wording requirements can change. Practitioners should verify the current position with the relevant body before arranging or renewing cover and should treat this guide as background context rather than a definitive statement of any body's current requirements. Readers who would like to discuss how the positions described apply to their own practice can speak to the team at Apex, or speak directly to the relevant professional body's standards team. Related background on PI more broadly is available on our professional indemnity insurance and architects' professional indemnity pages, and a general overview of when a professional body requires PI is set out at does my professional body require PI insurance. To get in touch, see our contact page.