Additional insured: what it means and how to verify it

Adding your firm to a vendor's insurance policy is the central mechanism of risk transfer in commercial contracts. Done right, you're covered. Done wrong (or not done at all), the COI looks fine and you're exposed.

What it actually does

When you require a vendor to add your firm as an additional insured on their general liability policy, you're asking their carrier to extend the protection of that policy to you, for liability arising out of the vendor's work for you.

Practically, that means: if a third party is hurt on a project and sues both you and the vendor, the vendor's insurer defends both of you and pays both of you (up to the policy limits). Your own policy doesn't have to answer first; theirs does. That's the risk transfer the contract is trying to achieve.

The endorsement landscape

On a standard ISO commercial general liability policy, the additional-insured status comes from a specific endorsement. The most common forms:

CG 20 10 — Additional Insured: Owners, Lessees, or Contractors — Scheduled Person or Organization. Covers ongoing operations. The version year matters: CG 20 10 04 13 is the 2013 version; older versions had broader coverage that some carriers no longer offer.
CG 20 37— Additional Insured: Owners, Lessees, or Contractors — Completed Operations. Covers completed operations: liability arising from the work after it's done.
CG 20 33 / CG 20 38 — Blanket additional-insured forms that cover anyone the named insured agreed in writing to add. Slightly different scope than CG 20 10/37; some risk managers prefer scheduled forms for clarity.
CG 20 26— Designated Person or Organization, for cases where the additional insured isn't a project owner or contractor.
On auto liability, additional-insured status typically requires CA 99 47 or a similar endorsement. The same logic applies — verify the endorsement is on the policy.

Most contracts require both ongoing and completed operations. Don't accept just one.

How to verify it on a COI

Find the "Description of Operations" box. Bottom of the Acord 25, free-text.
Look for explicit endorsement references. "[Your firm name] is named as an additional insured on General Liability per CG 20 10 and CG 20 37 where required by written contract" is the gold standard. Vague language like "additional insured per contract" without endorsement numbers is weaker.
Confirm both ongoing and completed ops.If only CG 20 10 is referenced, completed operations aren't covered.
Check the named insured matches the contract. The certificate is for the entity that holds the policy. If the contract is with a different legal entity (parent, DBA, subsidiary), the additional-insured status may not extend.
For high-stakes work, request the actual endorsement.The COI is a summary. The endorsement (CG 20 10 form, on carrier letterhead, with the policy number) is the binding document. For a major project, don't accept the cert alone.

Don't miss the endorsement reference at scale.

COIverify extracts the Description of Operations text, detects endorsement references, and flags certs where the named additional-insured language is missing or non-specific.

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Failure modes that cost real money

Cert says "additional insured" but no endorsement number. The cert may be informational only; the endorsement may not exist on the policy. Insurer could deny defense.
Only CG 20 10 (ongoing) referenced. Construction-defect claims often surface years later under completed operations. Without CG 20 37, you're uncovered on the most common late-stage claim type.
Old-version endorsement on a new contract. CG 20 10 11 85 (1985 version) is broader than CG 20 10 04 13 (2013). Some carriers won't issue the older version. The difference matters in court.
Named insured doesn't match.Contract is with "Acme Electric LLC"; cert is for "Acme Electric Holdings Inc." The additional-insured endorsement covers the Acme Electric LLC policy, not the Holdings policy. There may be no policy you're actually named on.
Endorsement dropped at renewal.Vendor renews policy but doesn't reattach the additional-insured endorsement. New COI says it's there; it isn't.

Additional insured is one of three risk-transfer levers on a standard COI. The other two are waiver of subrogation and primary and non-contributory. You almost always want all three together. And don't confuse additional insured with certificate holder — they are not the same.

Frequently asked questions

What does additional insured mean?

An additional insured is a party who has been added to someone else's insurance policy via an endorsement, giving them the right to be defended and indemnified by that policy as if they were the named insured (within the scope of the endorsement). It's the primary mechanism of risk transfer in commercial vendor contracts.

What's the difference between additional insured and named insured?

The named insured is the policyholder — the party who bought and pays for the policy. An additional insured is a third party added to that policy via an endorsement, with rights limited to what the endorsement specifies. The named insured has full policy rights; the additional insured has scoped rights for specific situations.

What's the difference between CG 20 10 and CG 20 37?

CG 20 10 covers the additional insured for liability arising out of the named insured's ongoing operations — i.e., while the work is happening. CG 20 37 covers the additional insured for completed operations — i.e., after the work is done but a problem with the work causes injury or damage. For construction projects, both are typically required.

How do I confirm I'm actually an additional insured?

Look at the 'Description of Operations / Locations / Vehicles' box on the COI. The text should reference the specific endorsement numbers (CG 20 10, CG 20 37 for ongoing and completed operations on GL) and explicitly name your firm or 'where required by written contract.' For high-stakes work, request a copy of the endorsement directly from the broker.

Can additional insured status be revoked?

It can be removed at the next policy renewal if the named insured doesn't renew the endorsement. This is one of the reasons expiration tracking is so important — at renewal, you need to verify all the endorsements are still on the new policy.

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