What a certificate of insurance (COI) is
A certificate of insurance, or COI, is a one-page summary that shows a client, landlord, or general contractor that your policies exist, with the carriers, policy numbers, dates, and limits. Insurance Code section 384 requires a certificate used in place of the policy to say it is not an insurance policy and does not amend, extend, or alter the coverage.
That statement is the reason a certificate cannot add coverage a contract asks for. If a lease or subcontract requires additional insured status or a waiver of subrogation, the policy needs an endorsement; writing it on the certificate alone does not create it. The ACORD 25 form is the common certificate for liability policies.
Most requests we get at the Stockton office come with a deadline: a job start, a lease signing, or a vendor setup. Bring the contract's insurance section so the certificate matches it. The full explainer is certificate of insurance, and the form is on ACORD 25.
Questions
What is a certificate of insurance?
A summary showing your policies, carriers, dates, and limits. Insurance Code section 384 says it is not the policy and does not change coverage.
Can a certificate add someone as additional insured?
No. Section 384 says the certificate does not amend or extend coverage. Additional insured status needs an endorsement on the policy.
What form is used?
The ACORD 25 is the common certificate for liability coverage.
Sources
- Insurance Code section 384 (leginfo.legislature.ca.gov, checked October 7, 2026). Required statement on a certificate or verification of insurance.
Related: Glossary · Stockton office · General liability · Esta página en español.