What Is Certificate of Insurance (COI)?

A COI functions purely as proof, not as a coverage document. It typically lists the named insured, the carrier, the policy number, the coverage types and limits, and the effective dates, formatted so a third party who is not a party to the actual policy contract can quickly confirm insurance exists without needing the full policy in hand. A general contractor asking a subcontractor to show proof of general liability coverage before work starts is the most common real-world use.

A COI is closely related to, but distinct from, two other terms in this glossary. A binder is temporary evidence that coverage has just gone into effect, before the formal policy is printed. A COI, by contrast, documents an already-issued, in-force policy and can be requested at any point during that policy's term, not just at binding.

A COI is also distinct from being named as an additional insured on a policy. A COI simply reports that a policy exists; it does not by itself extend any coverage to the party requesting it. If a client wants actual protection under someone else's policy, not just proof that a policy exists, that requires an additional insured endorsement, a different action entirely from issuing a certificate.