Professional Indemnity Insurance Glossary: Every Term Explained

Reviewed by Matthew Bartlett, Director, Apex Insurance Brokers Limited · Last reviewed 2026-08-05

PI policy wordings are dense with technical language, and the words carry real consequences: get the retroactive date or the notification rules wrong and a valid claim can fall outside cover. This glossary defines the terms that matter, in the order they tend to trip people up. Each entry is short by design so you can find, read and link to a single definition.

Core terms every policyholder should know

Claims-made basis. The dominant way PI cover is written. The policy that responds is the one in force when the claim is first made against you (or a circumstance is notified), not the one in force when you did the work. This is why continuous cover matters — a gap can leave old work unprotected.

Limit of indemnity. The maximum the insurer will pay. Commonly offered as generic options such as £1m, £2m or £5m. It may apply “any one claim” or “in the aggregate” — a crucial distinction (see below).

Any one claim. The full limit is available separately for each claim during the policy year, however many claims arise. Generally the stronger basis for the policyholder.

Aggregate limit. The limit is the total available for all claims in the policy period combined. Once exhausted, there is no further cover that year regardless of how many claims remain.

Excess (deductible). The amount you pay towards each claim before the insurer contributes. A higher excess usually lowers the premium but increases what you fund yourself.

Retroactive date. The date from which past work is covered. Claims arising from services performed before this date are excluded, even if the claim itself is made during the policy period. “Full retroactive cover” (or “retroactive date: none”) means no such cut-off.

Circumstance. An event or awareness — a complaint, an error you spot, a hint of a dispute — that may give rise to a claim but has not yet become one. Notifying a circumstance in time can secure the current policy to respond even if the actual claim lands years later.

Notification. The act of telling your insurer about a claim or circumstance. Claims-made policies typically require prompt notification, often “as soon as practicable” and within the policy period. Late notification is a common reason cover is disputed.

Cover structure and scope

Insuring clause. The core promise of the policy — the wording that sets out what triggers cover, usually “civil liability” arising from the conduct of your professional business.

Civil liability wording. The broadest common trigger. It responds to legal liability generally (breach of contract, negligence, breach of duty) rather than only to proven “negligence”, which is narrower and harder to establish.

Defence costs. The legal expense of defending or investigating a claim. Check whether these are in addition to the limit of indemnity or inclusive of it — inclusive costs erode the money available to settle the claim itself.

Costs inclusive vs costs in addition. “In addition” means defence costs sit on top of your limit; “inclusive” means they come out of it. For the same headline limit, “in addition” is more protective.

Aggregation. The mechanism deciding whether several related matters count as one claim or many. A wide aggregation clause can bundle multiple client losses into a single claim (one limit, one excess); a narrow one treats them separately. It cuts both ways depending on the excess and limit basis.

Run-off cover. Cover that continues to respond to claims after you stop trading, retire, sell or merge the business. Because PI is claims-made, a claim can arrive years after the work — run-off keeps a policy in force to meet it. Often arranged for six years, reflecting standard limitation periods.

Extended reporting period. A defined window after a policy ends during which you may still notify claims relating to earlier work. It is not the same as ongoing run-off cover and is usually shorter.

Quick-reference table

Why the wording matters more than the price

Two policies with the same £1m limit can behave very differently once you read how defence costs, aggregation and the retroactive date are set. A narrow aggregation clause with an “any one claim” limit and costs in addition is materially stronger than an aggregate limit with inclusive costs — even at an identical headline figure. If your profession is subject to a regulator (for example the SRA, RICS or ICAEW), minimum terms may also dictate limits, run-off and permitted excesses.

If any of these terms don’t match how you actually work, that’s worth a conversation before you renew. You can start a PI quote with Apex and we’ll sense-check the structure against your exposures.

Common questions

What is the difference between a claim and a circumstance?
A claim is a demand or allegation actually made against you. A circumstance is an early warning — something that might lead to a claim. Notifying a circumstance in the current policy year can lock in that policy to respond, even if the formal claim arrives much later.

Why does the retroactive date matter so much?
Because PI is claims-made, cover depends on when the claim is made, but the retroactive date limits which past work qualifies. Moving insurer and losing an early retroactive date can leave years of prior work uninsured, so continuity should be checked at every renewal.

Do I need run-off cover if I close my business?
Usually yes. A claim can surface years after you finish a job. Once your live policy lapses, only run-off cover keeps a claims-made policy available to respond to that historic work.

Apex Insurance Brokers Limited is authorised and regulated by the Financial Conduct Authority (FRN 724952). This guide is general information, not advice on a specific policy or a substitute for your policy wording.