A following form PI excess layer is an excess-of-loss professional indemnity policy that adopts — “follows” — the terms, conditions and definitions of the underlying primary policy, above an attachment point set at the primary limit. The excess layer drops down to respond only after the primary policy’s limit has been exhausted by a single claim or aggregated claims, and responds on substantially the same terms as the primary.
What “following form” means in PI insurance
Professional indemnity cover for firms wanting limits above what any one insurer is willing to commit is typically built as a “tower” of layers. The primary policy sits at the bottom and responds first. Above it sit one or more excess layers, each with its own limit and its own attachment point — the point at which it begins to pay. The total programme limit is the sum of the layers.
The phrase “following form” refers to how the excess layer wording relates to the primary. A true following form policy says, in effect, that it adopts the wording of the primary policy in all material respects: the same definitions of claim, circumstance, insured and professional services; the same exclusions; the same aggregation language; the same conditions; the same retroactive date. The excess layer’s own wording is short — typically a few pages — because its substantive terms are imported from the primary.
The alternative is a “stand-alone” or “self-contained” excess layer policy with its own complete wording. Stand-alone excess layers introduce the risk of coverage gaps: a claim covered by the primary policy may not fit within the narrower terms of the stand-alone excess, leaving the insured exposed for the portion of the loss that should have been covered by the higher layer. Following form policies are designed to eliminate this risk by ensuring the primary and excess wordings are co-terminous in scope.
In practice, no excess layer is perfectly following form. Most following form wordings carve out a small number of provisions and replace them with the excess layer’s own — typically aggregation, dispute resolution, governing law and notification provisions. These carve-outs are where the gaps live.
How following form excess layers work in practice
A standard PI programme for a UK firm needing meaningful limits looks like this. The primary policy is placed at a limit determined by the insurer’s appetite — typically £1m, £2m, £5m or £10m for mid-sized professional firms. Above the primary, an excess layer attaches at the primary limit and provides a further tranche of cover. Above that, a second excess layer attaches at the combined primary and first excess limits, and so on. The total tower can run to £25m, £50m, £100m or higher for the largest firms.
The excess layer responds when the primary policy is exhausted by paid claims. Exhaustion can occur on a single very large claim or — more commonly — through the accumulation of multiple claims over the policy year, where the primary policy is written on an aggregate basis (limit applies in aggregate across the year). For each-and-every-claim primary policies, exhaustion on a single claim is the more typical trigger.
The defence costs treatment matters. Where the primary policy includes defence costs within the limit (the UK norm for SRA-compliant solicitors’ PI under the MTC), defence costs erode the limit and accelerate exhaustion of the primary. The excess layer then responds to both indemnity and further defence costs. Where defence costs sit outside the limit (more common in some other professions), the excess layer is reached later.
The excess layer insurer usually has the right to “drop down” before exhaustion in defined circumstances — for example, where the primary insurer is insolvent or where the primary insurer is contesting cover in a way that an underlying layer is treated as having “failed” the insured. Drop-down provisions are negotiable but typically present in the wording.
Worked example
A mid-sized professional services firm with £4m fee income places a PI programme as follows. The primary policy is £2m each and every claim, written by Insurer A, with a £25,000 excess. A first excess layer of £3m sits above the primary, attaching at £2m, written by Insurer B on following form terms. A second excess layer of £5m sits above the first excess, attaching at £5m, written by Insurer C on following form terms. Total programme limit: £10m, with defence costs within the limit at each level.
A claim arrives valued at £6.5m including reserved defence costs. The handling proceeds as follows.
The firm pays the excess of £25,000. The primary insurer pays defence costs and indemnity up to £2m. The first excess insurer drops in at £2m and pays the next £3m. The second excess insurer drops in at £5m and pays the next £1.5m of the loss, leaving £3.5m of unused cover at the top of the programme available for any further development of the loss or for other claims in the year.
Now consider a variant. The aggregation language in the primary policy treats a series of claims arising from one originating cause as one claim. The first excess layer’s following form wording adopts the same aggregation test. The second excess layer’s wording, however, has its own aggregation language requiring a “single act, error or omission”. A claim valued at £6.5m on the primary insurer’s analysis (aggregated under originating cause) is reduced to several separate claims on the second excess insurer’s analysis (each act is a separate claim). The second excess layer may take the position that no single claim has reached the £5m attachment point and decline to respond on that basis, leaving £1.5m of the loss potentially uncovered.
This is the kind of gap that following form is meant to eliminate. A truly following form wording would have the second excess insurer adopt the primary aggregation language and respond in line with the layers below. Variation between layer wordings is where excess-of-loss recoveries get fought.
When following form matters most
Following form matters most in three situations.
First, on very large losses. Most claims are settled within the primary layer and never reach the excess layers. When a claim does reach the excess layers — typically a single very large matter or an aggregated series — the wording differences between layers become live and very valuable.
Second, when the firm’s exposure profile includes the kind of work most likely to produce a tower-penetrating loss. Audit partners on listed-company engagements, lead designers on major construction projects, transaction lawyers on complex M&A, large IT consultancies delivering critical infrastructure: all face the possibility of single losses that consume multiple layers of cover. For these firms, ensuring that the tower wordings are truly co-terminous is part of the risk management.
Third, on changes in the insurer line-up. If one of the excess layer insurers comes off the programme at renewal and is replaced by another, the new insurer’s standard following form wording may differ from the outgoing insurer’s. The replacement layer needs to be reviewed against the primary and against the other excess layers, not just placed on price.
Common variations and market wording
UK PI excess layer wordings typically use one of three styles. “Pure following form” wordings adopt the primary wording almost entirely, with a handful of standard layer-specific provisions. “Modified following form” wordings adopt the primary wording subject to a list of stated modifications — common modifications include aggregation, notification provisions and territorial scope. “Self-contained” wordings stand alone, with their own complete set of terms; these are less common in PI than in some other classes but appear at the top of large towers and from certain insurers.
For SRA-regulated solicitors, the primary layer must comply with the SRA Minimum Terms and Conditions, but the excess layers are not bound to MTC compliance. The market convention is for solicitors’ excess layers to be true following form on the MTC primary, but the wording should be checked. Excess layers above the SRA top-up that do not follow the MTC can introduce material gaps.
The “maintenance of underlying” condition is closely related. Most excess layer wordings require the insured to keep the underlying primary policy in force throughout the layer’s period. If the primary is cancelled or not renewed mid-policy, the excess layer may treat itself as effectively cancelled or may require the insured to step into the primary insurer’s shoes for the layer to continue to respond.
Excess of loss reinstatement provisions vary. Some excess layers reinstate after a loss; some do not. For each-and-every-claim policies the limit applies fresh to each claim, so reinstatement is generally not needed; for aggregate policies, reinstatement is more relevant.
Related concepts
Aggregation of claims is the principal area where following form matters: a wording difference on aggregation between layers can defeat the recovery on a large loss. Circumstance notification interacts because excess layer notifications need to be made within the relevant layer’s period. The SRA Minimum Terms and Conditions prescribe the primary layer wording for solicitors but not the excess layers.
Frequently asked questions
What is a following form PI excess layer?
A following form PI excess layer is an excess-of-loss professional indemnity policy that adopts the terms, conditions, definitions and exclusions of the underlying primary policy. The excess layer responds when the primary is exhausted, on substantially the same coverage terms, ensuring there is no gap in scope between the primary and excess cover.
How does an excess layer become “exhausted”?
An excess layer is exhausted when paid claims have consumed its full limit. The primary policy must first be exhausted before the excess layer is reached. Defence costs treatment matters: where defence costs are within the limit, they erode it and accelerate exhaustion; where defence costs are outside the limit, only indemnity payments erode the limit.
Are all excess layers following form?
No. Some excess layers are stand-alone with their own complete wording, and some are “modified following form” — adopting the primary wording subject to specified differences. Pure following form is the safest structure for the insured; modified or stand-alone wordings introduce the risk of gaps where the excess wording is narrower than the primary.
What is a “drop-down” provision in an excess layer?
A drop-down provision allows the excess layer to respond before the underlying primary is exhausted, in defined circumstances — for example where the primary insurer is insolvent or where coverage has failed at the primary level for reasons unrelated to the merits of the claim. Drop-down is negotiable but is a standard feature of well-drafted excess layer wordings.
What is the “maintenance of underlying” condition?
It is a condition requiring the insured to keep the primary policy (and any intervening excess layers) in force throughout the layer’s period. If the underlying policy is cancelled or replaced on materially worse terms, the excess layer may be treated as having lapsed or may require notification and consent to continue to respond.
Do excess layers cover defence costs?
Yes, on substantially the same basis as the primary policy. If the primary policy includes defence costs within the limit, the excess layer typically does the same. If defence costs sit outside the primary limit, they typically sit outside the excess layer limit too. Following form ensures these structural features carry across the tower.
Does an SRA-compliant primary policy require the excess layer to follow the MTC?
No. The SRA Minimum Terms and Conditions apply to the primary layer (and the SRA-mandated top-up to £2m or £3m for non-incorporated practices). Excess layers above the MTC top-up are not bound by the MTC and the wording is for negotiation. Market convention for solicitors is to use following form excess wordings that adopt the MTC primary terms.
How do I check that my tower is genuinely following form?
Read each layer wording against the primary. Identify which provisions the excess layer adopts and which it replaces. Pay particular attention to aggregation, notification, defence costs, territorial scope, dispute resolution and governing law. Ask the broker to confirm in writing that the tower is gap-free on the points that matter for your work.
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About Apex Insurance Brokers Ltd
Apex Insurance Brokers Ltd is a Bristol-based independent insurance broker authorised and regulated by the Financial Conduct Authority (firm reference number 724952), registered at Companies House under number 07014570. The firm advises UK professional service practices on Professional Indemnity and related covers. Contact: info@apexinsurancebrokers.co.uk or 0117 325 0027.
Last reviewed: May 2026 by Apex Insurance Brokers Ltd.
Important: this article is general information, not advice on your specific circumstances. For advice on PI insurance for your firm, contact us on 0117 325 0027 or info@apexinsurancebrokers.co.uk.