What Is a Certificate of Insurance (COI)?
By Wyatt Cooper · Published · 3 min read
Key takeaways
- A COI is a snapshot: it lists insurers, policy numbers, coverages, limits and dates as of the day it was issued.
- It is evidence of insurance, not the policy, and it cannot add coverage the policy doesn't have.
- GCs collect a COI from every sub before work starts and again whenever a policy renews.
A certificate of insurance (COI) is a one-page summary, usually issued by a contractor's insurance agent or broker, of the policies the contractor carries on the day it is issued: the insurers, policy numbers, coverage types, limits and policy dates. It is evidence of insurance, not the policy, and it cannot change or add to the policy's terms.
What a COI shows
Certificate of insurance: Harlow Electric
- Commercial general liability
- $1,000,000 each occurrence / $2,000,000 aggregate, expires May 31
- Automobile liability
- $1,000,000 combined single limit, expires May 31
- Workers' compensation
- Statutory limits; employer's liability $1,000,000, expires January 1
- Umbrella
- $5,000,000, expires May 31
- Certificate holder
- The general contractor, for the Larkspur Clinic project
How to check each box is in how to read a certificate of insurance; liability certificates are commonly issued on the ACORD 25 form. What else a GC collects is in what paperwork a GC requires from a sub.
A certificate is not the policy
Connecticut's insurance department puts it plainly: certificates "generally serve only as evidence of insurance in lieu of an actual copy of an insurance policy," they confer no rights on the holder, and they "cannot be used to amend, expand or alter the terms of the underlying insurance policy" (Connecticut Insurance Department, Bulletin S-14). Being listed as certificate holder does not make you insured: that takes an endorsement, explained in additional insured.
Contracts back COIs with notice duties. On federal installations, the contractor notifies the contracting officer in writing that required insurance is in place before starting, must keep it for the whole job, and must keep a copy of every subcontractor's proof of insurance (FAR 52.228-5).
How it works in Conflo
Conflo's compliance tracks general liability, auto, workers' comp and umbrella certificates for each company, with carrier, policy number and expiry, and marks each one valid, expiring within 30 days, expired, awaiting review or missing. A missing, expired or unreviewed required document puts that company on payment hold, shown on its commitments.
The bottom line
A certificate of insurance is the quick proof that a contractor is covered today, not a promise about tomorrow or a change to the policy.
Collect one before work starts, check it against the subcontract, and track every expiry date.
Sources
- Bulletin S-14, Use of certificates of insurance — Connecticut Insurance Department. Read October 22, 2026.
- FAR 52.228-5, Insurance—Work on a Government Installation — Acquisition.gov, U.S. General Services Administration. Read October 22, 2026.
Questions
Who issues a certificate of insurance?
The contractor's insurance agent or broker, on request. Ask the agent directly rather than accepting a copy from the sub, so you know it is current.
Is a certificate of insurance the same as an ACORD 25?
ACORD 25 is the standard form most agents use for liability certificates, but a COI can be on another form. Either way it is evidence of insurance, not the policy. Tracking renewals is in how to track subcontractor COIs.
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