Additional Insured
A person or entity added to another party's insurance policy, extending coverage to them for liability arising from the policyholder's work. Common in construction contracts where owners and general contractors require subs to add them as additional insured.
An additional insured is a party added to another party's insurance policy, receiving coverage for liability that arises from the policyholder's operations. It is the workhorse mechanism that allows project owners, general contractors, and upstream parties to benefit from subcontractors' insurance.
How It Works
A subcontractor carries general liability. The general contractor requires the sub to add them as an additional insured for the sub's work on the project. If the sub drops a tool and damages a homeowner's property, both the sub and the general contractor are potentially sued. Because the general contractor is an AI on the sub's policy, the sub's carrier defends both and pays within the sub's limits. The general contractor's own policy sits behind as excess or may not be triggered at all.
The Certificate and the Endorsement
Two documents matter. The certificate of insurance (COI) shows that coverage exists. The additional insured endorsement is the actual policy form that adds the named party. Best practice is to require both before work begins: the COI listing the AI, and the endorsement form number on the policy. A COI that lists someone as an AI without a matching endorsement may not deliver actual coverage.
Common Gotchas
Modern AI endorsements have become more restrictive than the forms used a decade ago. Some exclude work performed after completion. Some exclude the additional insured's own negligence. Some are capped at the underlying contract's requirements rather than the full policy limit. Owners and general contractors should read each endorsement carefully, not just the certificate, because the details determine what the coverage actually delivers.
Frequently asked questions
It extends the named insured's policy to cover the additional insured for liability arising out of the named insured's operations. If the named insured's work causes damage to a third party, the additional insured gets the same defense and indemnity that the named insured gets, for that specific exposure.
No. The certificate shows that coverage exists. The additional insured endorsement (AI endorsement) actually adds the party to the policy. A certificate alone does not grant coverage. Request both: a properly worded COI and the underlying endorsement.
Generally no. Most additional insured endorsements only extend coverage for liability arising from the named insured's work, not for the additional insured's own independent negligence. Contractors reviewing AI endorsements should look for language that makes this scope clear.
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