Certificate of Insurance Explained
A certificate of insurance (COI) is a proof-of-coverage snapshot used in U.S. business relationships. This guide explains what a COI shows, what it does not guarantee, and how to review COIs without getting tricked by paperwork.
Key takeaways
- A COI is evidence that a policy existed at the time it was issued, not a guarantee of coverage for your specific loss.
- The policy endorsements (like additional insured) matter more than what the COI “says.”
- COIs are common for leases, subcontractors, events, and vendor relationships.
- Use a simple checklist: limits, effective dates, policy types, and endorsements.
What a COI is (and is not)
A certificate of insurance is a standardized document (often an ACORD form) that summarizes key details about one or more policies: insurer, policy number, coverage type, limits, and effective dates.
What it is not: a contract that changes the policy. Most COIs state that they do not amend coverage and that the policy itself controls.
When you will be asked for one
- Leases: landlords request proof of general liability and sometimes property coverage.
- Client contracts: customers request proof of GL, E&O, or cyber depending on services.
- Subcontractors: you may request COIs from subs to avoid absorbing their losses.
- Events: venues often require COIs naming them as additional insured.
This sits directly at the intersection of contract risk and insurance structure.
How to read a COI
Focus on a few fields first:
- Named insured: who is actually covered by the policy
- Insurer and NAIC: which carrier issued it
- Policy type: GL, auto, workers’ comp, umbrella, E&O
- Limits: per occurrence and aggregate (where listed)
- Effective dates: are you inside the policy period?
If your contract requires specific endorsements, the COI alone is not enough—you need confirmation the endorsement exists.
Additional insured and other endorsements
Additional insured status is a policy endorsement that can extend certain protections to another party (often the client/landlord). The endorsement wording matters.
Other common endorsements include:
- Waiver of subrogation
- Primary and non-contributory wording
- Notice of cancellation (limited and policy-dependent)
See also: General Liability Insurance Explained and Commercial Umbrella Insurance Explained.
COIs, contracts, and risk transfer
Insurance requirements are a form of risk transfer. Contracts often push responsibility and cost onto whoever can best control the risk—or whoever has less leverage.
To avoid surprises, align:
- Contract insurance requirements
- What you actually carry
- What your policy endorsements actually say
For a practical contract review method, see Contract Risk Explained.
- Confirm the named insured matches the company you are hiring.
- Confirm coverage types match your contract (GL, auto, workers’ comp, E&O, umbrella).
- Confirm limits meet or exceed your contract requirements.
- Confirm effective dates cover the work period.
- If you require additional insured / waiver / primary wording, request proof of the endorsement.
- Store COIs centrally; set reminders for renewals.
FAQ
Does a COI mean the insurer will pay if there is a loss?
No. It means a policy existed. Whether a specific incident is covered depends on the policy and endorsements.
Can a COI add me as additional insured by itself?
Usually no. Additional insured status requires an endorsement on the policy.
What’s the biggest COI mistake?
Assuming the COI “proves” coverage for your scenario, without checking endorsements and contract language.