An additional insured is a person or organisation added to someone else's liability policy by endorsement, so that the policy responds to claims arising from the named insured's work or premises. The status is created by the endorsement on the policy. A certificate of insurance that notes additional insured status only reports it, and a certificate can report something that was never endorsed.
Updated September 2026.
Why brokers care
This is the single most common source of brokerage E&O claims involving certificates. A certificate goes out confirming additional insured status, the policy was never endorsed, and the gap surfaces only when a claim is tendered and declined. By then the client relied on the certificate and the brokerage is holding the exposure. Nothing about a wrong certificate looks different from a right one, which is why the check has to be deliberate rather than visual.
What to check
- That the endorsement actually exists on the policy, not just on the certificate
- Which form is used, since the coverage differs materially between them
- Whether it covers ongoing operations, completed operations, or both
- Whether the contract requires the status to be primary and non-contributory
- That the additional insured is named exactly as the contract specifies
Common mistake
Treating the certificate as proof. The certificate reports the status. Only the endorsement creates it, and the two diverge more often than anyone expects. Ask for the endorsement page rather than the certificate when the requirement is contractual, and confirm the form number rather than the wording in the description of operations box.
For the full sequence of checks, see the certificate review checklist.