A COI proves coverage exists; an endorsement actually changes your policy.
A common misconception: a COI listing someone as additional insured doesn't grant them coverage. Only an endorsement attached to your policy actually modifies your coverage terms. The COI is proof; the endorsement is the substance.
A Certificate of Insurance (COI) is simply proof that your policy exists and shows who is listed on it. An endorsement is an actual modification to your insurance policy that changes coverage terms. A COI listing someone as additional insured doesn't grant them coverage—only an endorsement attached to your policy does that. Think of the COI as the receipt and the endorsement as the actual product.
No, a Certificate of Insurance (COI) does not provide coverage—it only proves that a policy exists. Many vendors mistakenly believe that being listed as additional insured on a COI grants them protection. In reality, you need an actual endorsement attached to your policy to modify coverage terms and extend protection to them. The COI is documentation; the endorsement is the substance.
If a contract requires you to name someone as additional insured, you need both. The endorsement actually modifies your policy to extend coverage, while the COI proves that the endorsement exists. Request the endorsement from your insurance broker first, then have them issue a COI that reflects the change. The COI alone provides no coverage.
Definitions are educational and may be modified by your specific policy language, endorsements, and state rules. For regulatory guidance, refer to the California Department of Insurance or the NAIC.
Last updated: July 2026.