Additional Insured Endorsements: What They Are and Why Contracts Require Them

Your contract says the vendor must name you as an additional insured. Their certificate of insurance shows coverage. Those are not the same thing, and the gap between them is where a covered loss quietly becomes your problem. An additional insured endorsement is the piece that actually extends a vendor's policy to protect you, and confirming it is on every certificate is one of the most overlooked steps in insurance compliance. This guide explains what the endorsement is, why contracts require it, and how to verify you actually have it.

What an additional insured endorsement is

An additional insured endorsement is an amendment to a policy that extends its coverage to a party other than the named policyholder. When a vendor adds you as an additional insured on their general liability policy, their insurer agrees to defend and indemnify you for claims arising out of the vendor's work. Without it, you are a stranger to that policy: even if the vendor caused the loss, their insurer has no obligation to you, and you are left to pursue them and pay your own defense in the meantime.

Why contracts require it

Requiring additional insured status is how you push the risk of a vendor's work back onto the party creating it. If a subcontractor's crew causes injury or damage, you want their insurer responding first, not your own policy taking the hit and your loss history paying for it later. That is why well-written vendor agreements, and nearly every commercial lease, require the other party to name you as additional insured, often with a waiver of subrogation alongside it. The requirement is only worth anything if the endorsement is actually issued and on file.

The trap: a certificate is not the endorsement

Here is where compliance quietly fails. A certificate of insurance is a summary, and the box that says "additional insured" on a certificate is informational. It does not, by itself, grant you anything. The coverage is granted by the endorsement attached to the policy. A certificate can show the box checked while no endorsement was ever issued, and you would not know until a claim, when the insurer points out you were never actually added. Confirming the endorsement, not just the checkbox, is the whole job.

How to verify you are actually covered

For each vendor whose contract requires it:

• Get the endorsement form, not just the certificate (commonly a CG 20 10, CG 20 37, or a blanket additional insured form), and keep it on file with the certificate.
• Check it names you specifically or via a blanket "where required by written contract" wording that matches your agreement.
• Confirm it is current for the policy period the work happens in, and re-confirm at every renewal.
• Track it alongside the certificate so the requirement and the proof live together. A certificate of insurance tracking tool stores the certificate and its endorsements with the coverage, limits, and dates, and flags when any of it lapses, so an additional insured gap becomes an alert instead of a surprise.

Frequently asked questions

Is the additional insured box on the certificate enough? No. That box is informational. The actual coverage comes from the endorsement attached to the policy, so you need the endorsement form, not just the certificate.

What is the difference between additional insured and certificate holder? A certificate holder simply receives proof of insurance. An additional insured is actually covered by the policy. You usually want to be both, but only additional insured status protects you.

What is a blanket additional insured endorsement? A form that grants additional insured status to any party the policyholder is required by written contract to add, instead of naming each one. It is convenient, but you still need to confirm the form exists and its wording matches your contract.

Do leases require additional insured status too? Almost always. Commercial leases typically require the tenant to name the landlord as additional insured, which is why the lease's insurance terms and the tenant's endorsement should be tracked together.

Put it together

An additional insured endorsement is what turns a vendor's policy into protection for you, and a certificate checkbox is not proof that it exists. Require it in the contract, collect the actual endorsement form, confirm it names you and is current, and track it with the certificate so a lapse surfaces as an alert. That is the difference between assuming you are covered and knowing it.