What is an additional insured endorsement?

It's the page, issued by the insurer and attached to the policy, that adds you to a subcontractor's liability coverage. The certificate of insurance only reports it. The ACORD 25 says so in its own header: if the certificate holder is an additional insured, "the policy(ies) must have ADDITIONAL INSURED provisions or be endorsed", and "a statement on this certificate does not confer rights to the certificate holder in lieu of such endorsement(s)." A "Y" in the ADDL INSD column is the agent telling you the endorsement exists. The endorsement is what covers you.

This is general information, not legal or insurance advice.

What it gives you

Within the endorsement's terms, you're covered under the sub's policy for claims that come from the sub's work. When the sub's crew causes an injury and the injured person sues you as well, you can send that claim to the sub's insurer. Whether their insurer pays ahead of yours is a separate question, answered by primary and noncontributory wording (below).

The forms you'll see

Many additional insured endorsements are ISO forms; insurers also write their own. An ISO form's number and edition date are printed at the foot of each page, for example "CG 20 10 04 13".

Form	What it does
CG 20 10	Adds the person or organization named in its schedule, for the sub's ongoing operations: the work while it's being done.
CG 20 37	Adds the person or organization named in its schedule, for completed operations: claims from the work after it's finished.
CG 20 33	Blanket form. Adds anyone the sub agreed in a written construction contract to add, for ongoing operations, without naming them.
CG 20 38	Blanket form like CG 20 33 that also reaches the other parties your contract requires, such as the owner.
CG 20 01	Primary and noncontributory: when your contract requires it, the sub's policy pays before yours and doesn't ask yours to share.

Two things catch people out.

Ongoing isn't completed. CG 20 10 on its own doesn't cover a claim that arises after the sub has finished, such as a roof leak found a year after handover. If your subcontract requires completed-operations coverage, you need CG 20 37 or a form that includes it, kept in force for as long as the contract says.

Blanket forms depend on your contract. CG 20 33 and CG 20 38 cover you only because your written subcontract requires it. If the subcontract doesn't require additional insured status, a blanket form doesn't add you.

The edition date matters as well. ISO revises these forms, and the wording on the policy is the wording that applies, so check the edition attached rather than the one you remember.

How to check you're on the policy

1. Ask for the endorsement pages along with the certificate. On a blanket form, ask for the form and the page of the policy that lists it.
2. Check the named insured is the company you signed the subcontract with.
3. Check the form numbers against your subcontract: ongoing operations, completed operations if you require it, and primary and noncontributory if you require it.
4. Check the policy period covers the job, and for completed operations the years after it that your contract names.
5. Check again at renewal. A new policy comes with its own endorsements.

For a closer look at the individual forms, see additional insured endorsement forms and completed operations.

What TradeGuard does, and doesn't

TradeGuard reads who a certificate names as additional insured and tells you when it isn't you, or asks you when it can't tell. It doesn't read or verify the endorsement forms. For work where additional insured status matters, read the endorsement itself.

FAQ

Does a certificate of insurance make me an additional insured?

No. The endorsement does. The ACORD 25 says a statement on the certificate "does not confer rights to the certificate holder in lieu of such endorsement(s)". Ask for the endorsement pages.

What is the difference between CG 20 10 and CG 20 37?

CG 20 10 covers you while the sub's work is ongoing. CG 20 37 covers claims from the sub's work after it's completed. Subcontracts that need both ask for both, or for a form that includes both.

What is a blanket additional insured endorsement?

One that adds anyone the sub agreed in a written contract to add, without naming each one; CG 20 33 and CG 20 38 are the common ISO forms. It covers you only if your written subcontract requires additional insured status.

What does primary and noncontributory mean?

That the sub's policy pays a covered claim before yours and doesn't ask your insurer to share the cost. It comes from policy wording such as ISO's CG 20 01, and only applies when your contract requires it.