Sizing Your Professional Indemnity Limit: A Working Method

The limit of indemnity is the one number on a PI schedule you cannot look up — it has to be reasoned. This is the sequence we walk clients through.

Why the limit is the hardest number on the schedule

Almost every other term on a PI policy can be reasoned from the wording. The limit of indemnity is different: it is a judgement about how badly things could go wrong, made before anything has. Pick a limit that is too low and one serious claim leaves the firm exposed for the balance personally; buy far more than the risk justifies and you carry cost that does nothing for you. Sizing the limit properly means working through a handful of questions in order.

Start with what your contracts demand

The floor for your limit is usually set by other people. Client appointments, framework agreements, collateral warranties and public-sector procurement terms routinely specify a minimum level of PI that must be maintained, often for a stated period after the work completes. Read them — all of them, including the older ones still in force — because your limit needs to satisfy the most demanding live obligation, not the average one. If a contract requirement looks out of proportion to the engagement, that is a negotiation to have before signature, ideally with your broker sense-checking what the market will support.

Then think in worst-credible-claim terms

Contractual minimums are a floor, not an answer. The real question is: if the most serious piece of advice or design you currently have in circulation went wrong in the most damaging plausible way, what would it cost to put right? Not the worst imaginable outcome — the worst credible one. Useful prompts:

• What is the largest value your work influences? A consultant’s fee may be modest while the decision it supports — a building, a transaction, a system migration — is anything but. Claims track the loss caused, not the fee charged.
• Could one error propagate? Advice reused across many clients, a design detail repeated across a portfolio, or a template with a flaw in it can turn one mistake into many related claims.
• Who is downstream? Sophisticated commercial claimants, funders and insurers exercising subrogation rights tend to pursue losses fully and with good lawyers.
• How long is your tail? Work with long latency — structural design, tax planning, pension advice — must be sized against the future value of today’s work, not just this year’s.

Defence costs: inside or outside the limit?

Two policies with the same headline limit can deliver very different protection depending on how defence costs are treated. If costs are payable in addition to the limit, the full limit remains available for damages while insurers fund the defence separately. If costs are inclusive — within the limit — every pound spent on lawyers and experts erodes what is left to settle the claim itself. Professional disputes are document-heavy and expert-driven, and defence spend can be substantial even when the claim is successfully resisted. If your cover is costs-inclusive, size the limit with headroom for that erosion, or ask your broker what a costs-in-addition structure would take.

Any-one-claim versus aggregate

The basis of the limit matters as much as its size. An any-one-claim limit applies in full to each separate claim made during the period, however many there are. An aggregate limit is the total pot for the whole period: three claims share one limit, and once it is exhausted the policy has nothing left to give. Some aggregate policies soften this with one or more reinstatements, restoring the limit after it is used. When comparing quotes, an aggregate limit is simply not equivalent to the same figure any-one-claim, and contract clauses increasingly specify which basis is required — check yours before assuming compliance.

Professional-body expectations

If you are regulated or chartered, your professional body may prescribe minimum terms: a minimum limit (often scaled to the firm’s size or fee income), a required basis of cover, and sometimes an approved policy wording or participating-insurer arrangement. These regimes differ by profession and change over time, so treat the body’s current published requirements as the authoritative floor and confirm the detail with your broker rather than relying on what was true at your last renewal. Remember that a body minimum is calibrated for the profession at large — your own risk profile may justify more.

When excess layers make sense

Above a certain level, buying one big limit from one insurer stops being the efficient route. A layered programme places a primary policy up to an attachment point, with one or more excess-layer policies sitting above it, each responding once the layer beneath is exhausted. Layering is worth exploring when a contract demands a limit beyond your primary insurer’s appetite, when a single large project needs temporary extra headroom, or when splitting the risk across several insurers prices better than one carrier taking it all. The follow-form detail matters — excess layers should track the primary wording so there are no gaps between layers — which is exactly the sort of structuring a specialist broker exists to handle.

Revisit the number regularly

A limit sized correctly three years ago can be quietly wrong today. Trigger a review whenever you take on a materially larger contract, enter a new service line, sign a warranty or framework with insurance conditions, or notice claims inflation in your sector making settlements dearer. At Apex we treat the limit conversation as the starting point of every PI placement, not a box on a form — if you would like a second opinion on yours, we are happy to give one.

Apex Insurance Brokers Limited is authorised and regulated by the Financial Conduct Authority (FRN 724952). This page is general information, not advice; policy terms always take precedence.