TL;DR — Additional insured status extends a downstream party’s liability defense and indemnity onto your commercial general liability policy, but only for liability arising out of your work or the relationship the endorsement names — and only if the right CG 20 endorsement, primary-and-noncontributory wording, and waiver of subrogation are all in place. A certificate of insurance alone does not grant additional insured status.

Additional insured status on a commercial general liability (CGL) policy is the contractual mechanism that extends the policy’s liability defense and indemnity protection to a third party — typically a customer, landlord, general contractor, or other upstream entity — for claims that arise out of the named insured’s operations, premises, or completed work. Most commercial contracts ask for it. Most certificates of insurance reference it. Very few buyers can answer what the endorsement actually does — or which version of it is on the policy.

Additional insured status is one of the most-requested items in commercial contracts and one of the least-understood. At Avanti Group, we treat the additional insured wording as a structural review item on every commercial insurance program before binding, the same way we treat coinsurance and limits. A contract that demands “additional insured status, primary and noncontributory, with waiver of subrogation” but accepts a certificate of insurance without verifying the underlying endorsement is a contract that has not actually transferred risk. This article explains what the endorsement does, the difference between CG 20 10 and CG 20 37, what “primary and noncontributory” adds, why a certificate alone is not enough, and the three boxes a commercial contract should require.

What does additional insured status on a commercial liability policy actually do?

Additional insured status modifies a CGL policy by adding a third party as an insured under the named insured’s policy for liability arising out of the named insured’s operations, premises, or completed work — for the duration of the policy or the project, depending on the endorsement. It does not turn the third party into a full named insured, and it does not extend protection for liability that arises out of the third party’s own conduct or operations.

The practical effect is straightforward: if a claim is filed against both the named insured and the additional insured for something the named insured did, the named insured’s CGL policy can defend and indemnify both parties, subject to its limits and exclusions. The additional insured does not have to tender the claim into its own policy first. That shift — defense, allocation of indemnity, and preservation of the additional insured’s own loss history — is the entire economic value of the endorsement.

Additional insured status is also one of the standard categories that show up in any total cost of risk analysis: a contract that fails to transfer this risk leaves it sitting on the upstream party’s balance sheet whether the upstream party knows it or not.

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

The two ISO endorsements most commercial contracts care about are CG 20 10 and CG 20 37. They are not interchangeable.

• CG 20 10 — Additional Insured — Owners, Lessees or Contractors — Scheduled Person or Organization (or “Automatic” variants). Provides additional insured status for liability arising out of the named insured’s ongoing operations. Once the work is finished, CG 20 10 stops responding to that work.
• CG 20 37 — Additional Insured — Owners, Lessees or Contractors — Completed Operations. Provides additional insured status for liability arising out of the named insured’s completed operations — the products-completed operations hazard. This is the endorsement that responds when a roof installed two years ago fails today.

Most general contractors require both, on the same policy. A subcontractor that carries only CG 20 10 has bought a stub: it covers the project window, then disappears the moment the work is signed off. The exposure that actually generates litigation — completed-operations failures discovered later — sits uninsured against the upstream party’s contract demand. A quick check on the commercial declarations page and the schedule of forms tells you which versions are attached.

ISO has issued multiple revision years for both endorsements. The 2013 and later versions of CG 20 10 added a contractual prerequisite: the additional insured grant only applies to the extent the named insured agreed in a written contract executed before the loss. Older 2004-form versions read more broadly. This matters when an upstream party expects “automatic” additional insured status without a signed contract — a 2013-or-later endorsement will not deliver that.

What does “primary and noncontributory” add?

“Primary and noncontributory” is contract language that requires the named insured’s policy to (1) respond first, before the additional insured’s own policy, and (2) not seek contribution from the additional insured’s policy. Without this wording, two CGL policies covering the same claim default to “other insurance” treatment, often pro-rata by limits — meaning the additional insured’s own carrier ends up paying part of the claim and recording part of the loss history.

Primary-and-noncontributory wording is added either by endorsement (ISO CG 20 01) or by policy condition language. It is requested in nearly every meaningful commercial contract precisely because additional insured status without primary-and-noncontributory wording can leak losses back onto the additional insured’s policy through the “other insurance” clause. For Iowa contractors and trucking firms operating on midwestern construction sites and freight contracts, primary-and-noncontributory is now the default request, not an optional add.

Does a certificate of insurance grant additional insured status?

No. A certificate of insurance is informational only — it summarizes coverage that exists on a policy as of a date but does not create, modify, or extend coverage. ACORD certificate forms state this explicitly on the document itself. Additional insured status is granted by the policy endorsement, not by the certificate.

The practical implication is that a contract administrator who collects a certificate listing the upstream party as additional insured but does not collect a copy of the underlying CG 20 10 / CG 20 37 endorsements has no proof that the coverage was actually placed. When a claim arrives, the carrier responds based on what is in the policy. If the endorsement isn’t there, the certificate’s representation does not survive contact with the claim file.

The fix is procedural: the contract should require the named insured to provide both the certificate and the endorsements on binding, and on every renewal, before the upstream party authorizes payment. A renewal certificate that lists additional insured status while the new policy quietly dropped CG 20 37 is one of the most common quiet failures we see during a Business Risk Diagnostic™ review.

How does waiver of subrogation work alongside additional insured status?

A waiver of subrogation is a separate policy provision that prevents the named insured’s carrier from pursuing the additional insured to recover claim payments after a loss. Without it, the additional insured can be sued by the named insured’s carrier for amounts the carrier paid out — which defeats the point of the additional insured grant. Most commercial contracts now require additional insured status, primary and noncontributory, and waiver of subrogation, on both general liability and workers’ compensation policies.

For workers’ compensation specifically, the waiver of subrogation endorsement is what protects the upstream party from being sued by the subcontractor’s WC carrier after the carrier pays an injured worker. It is a different endorsement on a different policy, and it is frequently dropped from intake forms when a renewal carrier changes mid-program.

What are the three contract requirements that actually transfer risk?

The contract language that actually transfers risk on a commercial liability program comes down to three boxes:

1. Additional insured status on a written, signed contract executed before the loss, with both CG 20 10 (ongoing operations) and CG 20 37 (completed operations) endorsements on the named insured’s CGL policy, and the upstream party named on the schedule.
2. Primary and noncontributory wording, by endorsement (CG 20 01 or equivalent) or policy condition, so the named insured’s policy responds first and does not seek contribution from the upstream party’s policy.
3. Waiver of subrogation on both the CGL and the workers’ compensation policy, so neither carrier pursues the upstream party after a claim.

If any one of those three is missing, the risk transfer the contract intended is incomplete. The most reliable failure mode in the field is contracts that ask for all three but rely on a certificate of insurance to verify them — which a certificate cannot do. The fix is to collect the certificate and the underlying endorsements on bind, and to repeat that step on every renewal.

For Iowa contractors specifically, the Iowa Supreme Court has applied conventional indemnity and additional-insured analysis under Iowa law for decades, and the prerequisites in CG 20 10 (2013 and later) — written contract, executed before the loss — are enforced as written. A handshake “we’ll add you as additional insured” is not enforceable additional insured status under either the policy or Iowa contract practice.

The Business Risk Diagnostic™

Avanti Group treats the additional insured stack as a structured check inside the Business Risk Diagnostic™ — the pre-quote due diligence run before recommending any commercial insurance program. The Diagnostic pulls every active customer, landlord, and GC contract that requires additional insured status, verifies the actual endorsements on the in-force policy match what the contract requires, and flags any gap between the certificate language and the underlying CG 20 forms. Most accounts have at least one mismatch in the file the day we open the binder.

If the last commercial renewal handed back a certificate without anyone asking which CG 20 form is on the policy, the additional insured stack is usually where to start — it is one of the easiest categories of contract risk to fix in advance, and one of the most expensive to discover during a claim.

Frequently asked questions

What does additional insured status on a commercial liability policy actually do?

Additional insured status extends a CGL policy’s defense and indemnity protection to a third party for liability arising out of the named insured’s operations, premises, or completed work. It does not extend protection for liability arising out of the third party’s own conduct, and it does not turn the third party into a full named insured.

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

CG 20 10 grants additional insured status for ongoing operations — the active project window. CG 20 37 grants additional insured status for completed operations — claims arising after work is finished, typically the bulk of contractor litigation. Most general contractors require both. A subcontractor carrying only CG 20 10 leaves the completed-operations exposure unaddressed.

Does a certificate of insurance grant additional insured status?

No. A certificate of insurance is informational only — it summarizes coverage but does not create, modify, or extend it. Additional insured status is granted only by the policy endorsement (typically CG 20 10 and/or CG 20 37). The contract should require both the certificate and a copy of the underlying endorsement on bind and on every renewal.

What does primary and noncontributory add to additional insured wording?

Primary and noncontributory wording requires the named insured’s policy to respond first on a covered claim and not seek contribution from the additional insured’s own policy. Without it, “other insurance” clauses default to pro-rata sharing, and the additional insured’s policy ends up paying part of the loss and recording part of the loss history.

Why does a contract also ask for a waiver of subrogation?

A waiver of subrogation prevents the named insured’s carrier from pursuing the additional insured to recover claim payments after a loss. Without it, the carrier that just paid the additional insured’s claim under the additional insured grant can turn around and sue the additional insured for those same dollars. Most commercial contracts now require waiver of subrogation on both the CGL and the workers’ compensation policy.

Related reading

Other articles in the Commercial Foundations series:

• How to Demand and Verify Certificates of Insurance from Subcontractors — A COI is a snapshot, not a contract — three endorsements turn it from paperwork into protection.
• What General Liability Insurance Actually Covers and What It Doesn’t — The three coverage parts of a CGL, the named exclusions, and how per-occurrence and aggregate limits cap what gets paid.
• Policy Language That Quietly Limits Your Coverage: Sublimits, Exclusions, and Conditions — Three places a commercial policy quietly limits coverage—sublimits, named exclusions, and conditions.