The regulator’s minimum PI limit is a floor, not a target — and treating it as the latter is the most common underinsurance mistake in the professional services market.
A top-up PI policy is excess cover bought above a regulator-mandated or contract-mandated minimum limit. It is the practical answer to the gap between what a firm must hold to remain in business and what a firm actually needs to remain solvent after a worst-case claim. The economics are favourable because top-up capacity is materially cheaper per pound than primary cover. The mechanics are straightforward but easy to get wrong, particularly where the underlying primary is a regulator-prescribed wording with its own minimum terms. This guide explains when buyers should consider a top-up, how to size it, and where the placement traps sit.
UK professional firms face a patchwork of regulator-set minimum PI limits. The Solicitors Regulation Authority Minimum Terms require a £2m minimum limit for sole practitioners and partnerships and a £3m minimum for incorporated practices, on each and every claim, with no aggregate. The RICS regime requires graduated minimums of £250,000, £500,000 or £1m primary depending on fee income, with aggregate limits permitted for many segments. The Architects Registration Board requires a minimum of £250,000 for individual architects and £1m where the work includes residential dwellings within scope of the Building Safety Act 2022 regime. The Institute of Chartered Accountants in England and Wales sets minimum cover at the higher of £1.5m or 2.5 times fee income, with a cap of £30m. Financial advisers regulated by the FCA are subject to MIPRU 3.2 limits that scale with income.
None of these minimums are designed to be commercially adequate for a firm with material exposure. They are a regulatory floor calibrated to make the regulated population insurable in aggregate. Individual firms vary widely: a single substantial transaction, a residential project under the Building Safety Act, a contractually mandated higher limit imposed by a client or main contractor, or simply a fee size that exceeds the regulator’s assumed profile will all push the firm above the minimum.
A top-up policy sits above the regulator-mandated primary and provides excess cover on a follow-form or standalone basis. The buyer is the firm itself. The premium for a top-up is typically a fraction of the primary rate per pound of limit — often 30% to 60% of the primary rate per million for the first top-up layer, with rates flattening further as the tower extends. The mechanics are the same as for any excess layer (see Excess layer PI insurance) but the regulatory dimension makes top-ups distinct from purely commercial excess placements.
The triggers for buying a top-up are usually identifiable in advance. A single client with fees representing more than 10% to 15% of total revenue is one. Residential work falling within the scope of the Building Safety Act 2022 is another, because the thirty-year retrospective tail under section 135 of the Act materially extends the period in which a large claim can crystallise. A contractual demand for a higher limit from a substantial client is a third — the cost of a top-up is usually less than the cost of declining the engagement. A merger, a lateral hire, or a move into a more exposed practice area each warrant a fresh look at the limit.
A top-up policy responds when the primary limit has been eroded or exhausted by claims notified during the period of insurance. Its insuring clause typically mirrors the primary, with three carve-outs that matter: the attaching point, the limit, and the conditions specific to the excess layer.
Where the primary is a regulator-prescribed wording — the SRA Minimum Terms wording for solicitors, the RICS Minimum Approved Wording for surveyors — the top-up should ordinarily follow that wording on a follow-form basis. The SRA Minimum Terms include conditions that the regulator considers non-negotiable, such as the prohibition on rescission and the avoidance restrictions, and any conflict between the primary and the top-up is resolved in favour of the more protective primary so far as the SRA’s mandatory clauses are concerned. The top-up wording should expressly acknowledge the primary’s minimum terms and respond consistently.
For non-prescribed primaries — most commercial PI placements — the top-up wording question is the same as for any excess layer. Follow-form is usually safer, standalone is acceptable with explicit alignment on key terms.
The aggregation question matters more for top-ups than for many other coverage decisions because the regulator-mandated minimum often applies on an each-and-every-claim basis (with no aggregate), while the top-up may apply on a different basis. The SRA Minimum Terms expressly require the primary £2m or £3m limit to apply to each claim without aggregation. A top-up policy that aggregates above that primary creates an unexpected gap: the primary will pay the first £2m of each separate claim in a series, but the top-up may apply a single aggregate to the series. The cases on aggregation — AIG Europe Ltd v Woodman [2017] UKSC 18 in particular — make clear that the interpretation depends on the precise wording of the relevant clause. The practical answer is to align the aggregation basis of the top-up with the primary where the primary is non-aggregated.
The Building Safety Act 2022 has put pressure on the top-up market for residential design. Section 135 of the Act extended the limitation period under section 1 of the Defective Premises Act 1972 to thirty years for accrued causes of action. Architects, structural engineers and surveyors with residential exposure are seeing larger and longer claims and are increasingly buying top-up limits that would have been considered excessive five years ago. The market response has been to maintain capacity at primary level — often via the regulator’s minimum wording — while pricing excess and top-up layers more carefully and applying tighter conditions on residential exposure.
A six-partner architectural practice holds an SRA-equivalent primary limit through its ARB-compliant wording of £1m. The firm has historically worked on commercial offices and warehousing where £1m has been adequate. In 2024 it wins a substantial mixed-use scheme with 120 residential units, taking on responsibility for design coordination. The contract requires £5m PI cover, and the project triggers Building Safety Act 2022 exposure.
The broker arranges a top-up of £4m excess of the £1m primary at a premium of £11,000, against a primary premium of £6,500. The total tower is £5m at a combined cost of £17,500, satisfying the contract requirement and addressing the longer Defective Premises Act tail.
In 2027 a claim emerges from the residential scheme alleging negligent specification of a facade component contributing to remedial costs of £4.2m. The primary pays its £1m limit. The top-up responds on a follow-form basis and pays a further £3.2m, exhausting at £4.2m total payment. The firm’s contribution is limited to its policy excess.
Had the firm continued at £1m primary alone, it would have faced an uninsured exposure of £3.2m. The £11,000 top-up premium, paid over four years, was £44,000 of cumulative cost — against a £3.2m uninsured loss avoided.
Map the firm’s actual exposures against the regulator’s minimum every year. Where the gap is material — a single large client, residential work, a high-value contract — quantify the top-up needed.
Ask the broker for a tower comparison: primary cost per pound, top-up cost per pound, total cost per pound of limit. The relative cost of additional limit is almost always cheaper per pound than the primary, and that ratio should drive the conversation.
Confirm that the top-up wording is genuinely follow-form to the primary, including on aggregation, retroactive date and notification clauses. Where the primary is a regulator-prescribed wording, the top-up should expressly acknowledge that and respond consistently.
Re-test the limit at any structural change in the firm — a new partner, a lateral hire bringing a new client portfolio, a new sector, or a new contractual requirement from an existing client.
Document the limit decision. A short note on file recording the firm’s reasoning for the chosen limit is useful evidence of due care in the event of a future under-coverage dispute.
Apex’s view: too many regulated firms treat the regulator’s minimum as the right answer rather than the floor it actually is. The premium gap between regulatory minimum and a commercially adequate tower is rarely material — often a four-figure additional spend on a five-figure base. The exposure gap between the two is potentially career-ending. Where a firm has any residential exposure under the Building Safety Act 2022, any single client over 10% of fees, or any contract requiring more than the regulator’s minimum, the conversation should default to “buy the top-up” and only move off that default if there is a clear reason. We have yet to see a firm regret having bought more limit than the regulator required after a serious claim.
Apex Insurance Brokers serves UK professional services firms and commercial businesses. Call 0117 325 0027, email hello@apexinsurancebrokers.co.uk, or request a quotation.
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