What is a Certificate of Insurance (COI)?
A COI is the standard one-page summary of an in-force commercial insurance policy. It includes the named insured, policy numbers, effective and expiration dates, lines of coverage, per-occurrence and aggregate limits, and the certificate holder (the recipient). The COI is informational — it does not change the policy, does not extend coverage to anyone, and does not amend any terms.
What is an Additional Insured endorsement?
An additional insured endorsement is an amendment to your policy issued by the carrier that extends certain coverage rights to a named third party — typically a venue, a property owner, a GC, or a corporate sponsor. The added party becomes an insured under your policy for the limited scope of work or events specified.
Common additional-insured forms in use today:
- CG 20 10 — additional insured for ongoing operations
- CG 20 37 — additional insured for completed operations
- CG 20 26 — additional insured for designated person/organization (broad)
- CG 20 11 — additional insured for premises managers
Different forms cover different scopes. Read the contract carefully to identify the required form name; the carrier issues whichever form matches the contract language.
Side-by-side comparison
| Feature | Certificate of Insurance | Additional Insured |
|---|---|---|
| Type | Informational summary | Policy amendment |
| Effect on coverage | None — proof only | Extends coverage to a named party |
| Issued by | Agency, on behalf of carrier | Carrier, with policy endorsement |
| Contains policy details? | Yes — limits, dates, holders | Yes — names the added insured and scope |
| Common form numbers | ACORD 25 (most common) | CG 20 10, CG 20 37, CG 20 26, CG 20 11 |
| Typical issuance time | Within 24 hours | Within 24 hours (with the COI) |
Certificate holder vs additional insured
A common confusion: the "certificate holder" field on a COI does not make the holder an additional insured. The certificate holder simply receives a copy of the COI and (per ACORD 25 form language) a notice if the policy is canceled. Adding an additional insured is a separate request that triggers a carrier endorsement.
If a venue contract says "name us as additional insured," the venue must be added by endorsement — listing them only as certificate holder is insufficient.
When you need each
- COI alone: proof-of-insurance requests where the recipient is not exposed to your operations (e.g. a state license board, a vendor verifying coverage exists).
- COI + additional insured: almost any venue, landlord, GC, school district, or corporate event contract where the recipient could be sued because of your operations.
- Waiver of subrogation: a third related endorsement often requested in the same contract; gives up the carrier's right to recover from a specific party after paying a claim.