An additional insured is a person or organization granted insured status on someone else's liability policy, almost always by endorsement, because a contract requires it. The status is limited: the additional insured is covered only for liability arising out of the named insured's work, premises, or operations, not for its own unrelated exposures.
You will meet the term in contracts. A landlord requires it of tenants, a general contractor requires it of every subcontractor, and a project owner requires it of the general.
Additional Insured
A party added by endorsement to another organization's liability policy, receiving insured status limited to liability arising out of the named insured's operations, work, or premises.
Why do contracts require additional insured status?
Three protections drive the requirement. First, it backs up the indemnity language: contracts pair a hold harmless agreement with additional insured status so that if a statute or court voids the indemnity, the insurance still responds. Practitioners call it the belt and suspenders approach.
Second, the endorsement buys a defense. When both parties are sued over the named insured's work, the insurer defends the additional insured too, and if the additional insured meets its policy duties those defense costs are paid as supplementary payments outside the limit of insurance.
Third, it blunts subrogation, since insurers generally do not pursue recovery from their own insureds on the same policy. Sophisticated contracts go further and demand the coverage be primary and noncontributory, so the additional insured's own policy sits untouched.
How is additional insured status actually added?
Under ISO forms it takes an endorsement, full stop. The workhorse is CG 20 10, which covers the scheduled party for liability arising from the named insured's ongoing operations. Completed operations exposure, the source of most construction claims, needs a separate endorsement, so a contract that says "including completed operations" is asking for CG 20 37 alongside CG 20 10.
Some carriers write blanket additional insured wording into proprietary forms, triggered whenever a written contract requires the status.
The edition date matters too: post 2004 editions add "caused in whole or in part" language, requiring the named insured to be at least partly responsible before the additional insured is covered. A certificate reviewer who rejects your COI because it names the endorsement but not the edition date is doing exactly this analysis. The full form family is covered in our guide to additional insured endorsements.
Frequently asked questions
What is the difference between an additional insured and a certificate holder?
An additional insured has actual coverage rights under the policy through an endorsement. A certificate holder merely receives a certificate showing coverage exists and has no rights under the policy at all. A certificate alone never creates additional insured status.
Does an additional insured pay for the coverage?
Not directly. The named insured buys the endorsement, and many carriers charge a per endorsement fee or build blanket status into the premium. The real cost lands on the named insured's policy, whose limits and loss history absorb the additional insured's claims.
Does additional insured status cover the additional insured's own negligence?
Usually only partially. Current ISO endorsements cover the additional insured for injury caused in whole or in part by the named insured, and many states bar coverage for the additional insured's sole negligence. Older 1985 edition wording was broader. Edition dates decide this.
Can additional insured status apply after the job is finished?
Only with a completed operations endorsement such as CG 20 37. CG 20 10 alone stops at ongoing operations, which is why construction contracts commonly require both forms and why certificate reviewers check for the pair.
This definition is for educational purposes. Your policy's specific terms, conditions, and endorsements control. Talk to a licensed broker about your actual exposures.