Additional insured endorsements

Category: Policy wordings and clauses · Reviewed by the Apex broking team · Last reviewed 2026-08-22 · ~6 min read

What the endorsement is trying to achieve

Commercial contracts routinely oblige one party to protect another through insurance. A construction contract requires the contractor to protect the employer; a lease requires a tenant to protect the landlord; a supply agreement requires the supplier to protect the customer. The drafting shorthand is often “name us as an additional insured”. What the requesting party actually wants is usually one or more of three things: the ability to claim on the policy in its own right; protection against the insurer turning round and suing it after paying; and visibility that the cover exists and is maintained.

Those are three different requests and they are satisfied by three different mechanisms. Agreeing to the shorthand without deciding which one is meant is how contractual insurance obligations end up unperformed.

Joint insured, composite insured and the difference between them

Where two parties are added as joint insureds, the law treats their interest in the subject-matter as the same interest. Their rights stand or fall together, and conduct by one that prejudices the policy — a misrepresentation at placement, a fraudulent claim, a breach of a condition — can affect the other.

Where they are composite insureds, each is insured in respect of its own separate interest, and the contract operates as a bundle of separate contracts between the insurer and each insured. That is the position commonly taken for parties with genuinely different interests in the same property or project. The practical significance is defensive: on a composite basis, one insured’s misconduct or breach does not automatically destroy another’s cover. A severability clause is often added to make that intention explicit rather than leaving it to be argued about after a loss.

The distinction is decided by the substance of the interests insured and the wording used, not by the label on the endorsement. If the intention is composite, the wording should say so.

Noting an interest is not the same as being insured

A very common request is that a party’s interest be “noted” on the policy. Noting an interest records that a third party has an interest in the insured subject-matter. On its own it does not make that party an insured, does not give it a right to claim, and does not prevent the insurer exercising subrogation rights against it. In practice its principal value is administrative — the noted party is more likely to be told if the policy is cancelled or materially altered, if the endorsement says so.

Where a contract says “note our interest” but the commercial expectation is that the party can actually recover under the policy, the contract and the endorsement are pulling in different directions. This is one of the most frequent mismatches we see between contract wording and policy wording.

Indemnity to principals and waiver of subrogation

On liability policies the UK market device that most closely mirrors a North American additional insured endorsement is an indemnity to principals extension. It extends the policy so that, in respect of work carried out by the insured, the policy will indemnify a principal against liability in the same way it would indemnify the insured, usually subject to the principal observing the policy terms and to no wider cover than the insured itself enjoys. It does not turn the principal into a policyholder for all purposes.

A waiver of subrogation does something narrower and purely defensive: the insurer gives up the right to pursue the named party in the insured’s name after paying a claim. It gives the protected party no right to claim on the policy at all. Because the waiver depends on the insurer agreeing to it, a contractual promise to obtain one should be checked against the policy before the contract is signed rather than after.

On property and construction risks the equivalents are co-insurance of the employer under a construction all risks policy and, on liability, the principals indemnity. Which of these a JCT or NEC arrangement expects depends on the insurance option selected in the contract.

What adding a party actually costs you

Adding an insured does not add a limit. Unless the endorsement provides otherwise, the added party shares the same limit of indemnity, the same aggregate, the same excess and the same exclusions as the original insured. A large claim by the additional insured erodes the cover available to the policyholder who bought and paid for the policy.

There are duties too. Additional insureds may acquire notification obligations, and their conduct may be relevant to the insurer at renewal. On a joint basis, their conduct may be relevant to the policy’s validity. Before agreeing to a blanket contractual obligation to add anyone a counterparty nominates, it is worth knowing how many parties that could turn out to be.

Why it matters

Insurance obligations in commercial contracts are usually negotiated by people who will never read the policy, and honoured by people who never read the contract. The gap between the two is where uninsured liability sits. The fix is procedural rather than clever: read the insurance clause before signing, decide which of the four mechanisms it actually requires, and get the endorsement issued and checked rather than assumed.

Frequently asked questions

Is 'additional insured' a UK insurance term?

Not natively. It comes from North American liability practice. UK commercial wordings achieve comparable results through joint or composite insured status, noting of interest, an indemnity to principals extension, or a waiver of subrogation. A contract asking for an additional insured should be translated into whichever of those is actually intended.

Does noting a party's interest give them the right to claim?

No. Noting an interest records that a third party has an interest in the insured property. It does not make them an insured, does not give them a right of recovery under the policy, and does not stop the insurer pursuing them by subrogation. If the commercial intention is that they can claim, they need to be added as an insured.

What is the difference between joint and composite insureds?

Joint insureds share a single interest, so their rights stand or fall together and one party's breach or misrepresentation can prejudice the other. Composite insureds are each insured for their own separate interest, so the policy operates as separate contracts and one insured's conduct does not automatically destroy another's cover.

Does adding an additional insured increase the limit of indemnity?

No, unless the endorsement expressly says so. The added party normally shares the same limit, aggregate, excess and exclusions. A claim by the additional insured erodes the cover available to the original policyholder, which is a point worth raising when a contract requires several parties to be added.

Related entries

• Subrogation
• Severability clause
• Public liability insurance
• Construction all risks insurance
• Net contribution clause

This entry is part of the Apex Insurance Wiki. This entry is insurance information, not legal advice. It describes UK insurance law and market practice as at August 2026 and does not address the terms of any particular policy. Take advice on your own wording and your own facts before acting. Last reviewed 2026-08-22. Next review: 2027-02-22.

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