The Types of Additional Insured Endorsements — and Why the Wrong One Leaves a Gap

"Just name us as additional insured." It's the most common insurance request in any contract — and one of the most misunderstood. Additional insured status isn't one thing; it's a family of endorsements, each covering a different party, a different time period, or a different exposure. Which one is actually attached decides whether the protection you were promised is really there.

Get the right form and the risk transfer works. Get the wrong one — or rely on a certificate instead of the endorsement — and the coverage can simply not respond when a claim arrives. Here are the main types and where each fits.

First: what additional insured status actually does

Adding someone as an additional insured extends *your* liability policy to cover *them* as an insured, for liability connected to your work or your premises. It's how risk flows through a contract: a general contractor requires subcontractors to add the GC (and often the owner) as additional insureds, so the subs' policies defend and pay when the GC is pulled into a claim arising from the subs' work.

Two things are true of every form. First, a certificate of insurance does not grant it — the certificate is just evidence; only the endorsement on the policy adds anyone (see certificate of insurance vs. additional insured). Second, modern endorsements generally limit the additional insured's coverage to the extent of the named insured's fault — more on that below.

Scheduled vs. blanket

The first fork is *how* the other party is added:

• Scheduled endorsements name the additional insured on the form. The GC or owner is listed specifically. Precise, but it has to be requested and issued for each party.
• Blanket (automatic) endorsements add anyone the named insured is required by written contract to add, without naming them. Convenient for a contractor juggling many contracts — but status only attaches where a written contract actually requires it, so the contract wording carries the weight. Common ISO blanket/automatic forms include CG 20 33 (automatic status when required in a construction agreement with the named insured) and CG 20 38 (which can extend status further up the chain to parties the named insured doesn't directly contract with).

Many carriers also create "blanket" effect by putting contract-triggered language into a scheduled form. Either way, the question is the same: does the form grant status to the party your contract names, and on what terms?

Ongoing vs. completed operations — the gap that bites

This is the distinction that causes the most uncovered claims in construction:

• CG 20 10 — *Additional Insured – Owners, Lessees or Contractors – Scheduled Person or Organization* — adds the other party for liability arising from the named insured's ongoing operations: while the work is being performed.
• CG 20 37 — the completed-operations counterpart — covers the period after the work is finished.

Here's the trap. A subcontractor finishes electrical work and demobilizes. Months later, faulty wiring causes a fire. That's a completed-operations claim — and a policy with only CG 20 10 (ongoing operations) may not respond for the GC at all. If the contract wanted protection during *and* after the work and only the ongoing-operations form was attached, nobody notices the gap until the fire. Contracts that care about long-tail construction-defect exposure should require both forms — and the coverage should be confirmed, not assumed. (This is the same long-tail defect world as the action over exclusion and contractual liability.)

The special-purpose forms

Beyond the owners/lessees/contractors forms, several endorsements add specific parties for specific relationships:

• Managers or Lessors of Premises (CG 20 11) — adds a landlord as additional insured on a tenant's policy, for liability arising from the tenant's use of the leased space. The standard ask in a commercial lease.
• Lessor of Leased Equipment (CG 20 28, or CG 20 34 for automatic status) — adds the company that leased equipment to the named insured, for liability tied to that equipment.
• Vendors (CG 20 15) — adds a distributor or retailer that sells the named insured's product, for liability arising out of the product — common in manufacturing and distribution supply agreements.
• Designated Person or Organization (CG 20 26) — a general additional-insured form used where the specific relationship forms don't fit.

Using the right relationship form matters: a landlord added on a tenant's policy with an owners/lessees/contractors form instead of the managers/lessors of premises form may not get the coverage the lease intended.

The fine print: editions and "the extent of the named insured's fault"

Two details quietly change how much coverage an additional insured actually gets:

• Edition date. ISO has revised these forms over the years. Newer editions (the 2004 and 2013-era revisions) narrowed coverage to liability "caused, in whole or in part, by" the named insured — meaning the additional insured is covered to the extent of the named insured's fault, not for the additional insured's own sole negligence. Older editions ("arising out of") were broader. A contract that just says "CG 20 10" with no edition date can be satisfied by narrower wording.
• Limits capped by contract. Some current editions cap the additional insured's coverage at the limits the contract required, even if the policy carries more.

None of this makes the endorsements bad — it makes reading them (and the contract) essential.

How to make sure you actually get the right one

1. Read what the contract requires — ongoing *and* completed operations? Scheduled by name or blanket? A specific edition date? 2. Match the endorsement to the relationship — owners/lessees/contractors for construction, managers/lessors for a lease, vendors for product sales. 3. Confirm the endorsement is attached — request a copy of the actual endorsement, not just a certificate. 4. Pair it with the other two requirements — most contracts also demand a waiver of subrogation and primary and non-contributory coverage; additional insured status is only one leg of the three.

For the broader picture, see business insurance for contractors and our general contractor insurance overview.

Our approach

At Cory Washington & Co., we don't just check the "additional insured" box on a certificate — we read the contract, match the right endorsement to the relationship, confirm ongoing *and* completed operations where the deal calls for it, and verify the actual form (and edition) is on the policy. The goal is that the party you promised to protect is protected on the terms the contract actually requires — and that the waiver of subrogation and primary and non-contributory pieces are in place alongside it.

Lining up a contract's insurance requirements, or not sure which endorsements your policy carries? Request a quote or a policy review and we'll read the forms with you.

Frequently Asked

This article is general information for business owners, not insurance or legal advice, and does not bind or alter coverage. Policy terms, eligibility, and pricing vary by carrier and state — confirm specifics with our licensed team before making decisions.