Additional Insured Endorsement Explained: CG 20 10 vs CG 20 37

An additional insured endorsement is a modification to a commercial general liability (CGL) insurance policy that extends coverage to a third party — typically a project owner, general contractor, or property manager — for claims arising from the named insured's operations. The two most important additional insured endorsement forms are CG 20 10, which covers ongoing operations, and CG 20 37, which covers completed operations. Together, they provide the full scope of additional insured protection that most commercial contracts require.

Understanding the difference between these endorsements is not an academic exercise. It is the difference between having insurance coverage when a construction defect claim arrives three years after project completion and discovering that your additional insured protection ended the day the subcontractor packed up their tools. For operations managers responsible for vendor compliance, this is one of the most consequential details on a certificate of insurance.

What Additional Insured Status Actually Means

When your organization is named as an additional insured on another party's CGL policy, you gain the right to be defended and indemnified under that policy for certain claims. This is a powerful risk transfer mechanism because it means the other party's insurance responds to claims against you — claims that arise from their work, their products, or their operations.

Additional insured status is different from being a named insured. The named insured is the entity that purchased the policy and has full rights under it, including the right to cancel, modify, or receive return premiums. An additional insured has narrower rights, limited to defense and indemnification for claims within the scope of the endorsement.

There are several critical limitations to understand:

Additional insured coverage only applies to claims arising from the named insured's acts or omissions, not from your own negligence (under the current CG 20 10 04 13 edition)
The additional insured's coverage is subject to the same policy limits, exclusions, and conditions as the named insured's coverage
If the named insured's policy is canceled or lapses, the additional insured's coverage disappears with it
The additional insured does not have the right to receive policy cancellation notices directly from the insurer (despite what many people believe)

This last point is why ongoing COI monitoring is essential. The certificate may say "30 days notice of cancellation," but the ACORD 25 form itself includes a disclaimer that this language confers no obligation on the insurer to provide such notice. Your only reliable protection is proactive compliance tracking.

CG 20 10: Additional Insured — Ongoing Operations

CG 20 10, formally titled "Additional Insured — Owners, Lessees or Contractors — Scheduled Person or Organization," provides additional insured coverage for bodily injury and property damage that occurs during the named insured's ongoing work.

The key characteristics of CG 20 10 include:

Scope — Covers claims arising from the named insured's ongoing operations performed for the additional insured
Time trigger — The bodily injury or property damage must occur while the named insured's work is in progress
Causation requirement — Under the 04 13 edition, coverage applies only to liability caused in whole or in part by the named insured's acts or omissions
Schedule — The endorsement includes a schedule identifying the additional insured entities by name, and may reference a specific project, contract, or location
Duration — Coverage extends only while the named insured's operations are ongoing; it does not survive completion of the work

The 04 13 (April 2013) edition of CG 20 10 is the most commonly used version today. It narrowed the scope compared to earlier editions. The 07 04 (July 2004) and 10 01 (October 2001) editions provided broader coverage because they did not include the "caused in whole or in part by" language, meaning coverage could apply even if the additional insured bore some fault. If you have the option, earlier edition dates generally favor the additional insured, but most insurers now issue only the 04 13 edition.

What CG 20 10 Covers: An Example

A general contractor (GC) hires a plumbing subcontractor and requires additional insured status on the sub's CGL policy. While the plumbing work is in progress, a pipe joint fails and floods the building, causing $200,000 in damage. The building owner sues both the GC and the plumbing sub.

With CG 20 10 in place, the GC is an additional insured on the plumbing sub's policy. The sub's insurer must defend the GC and potentially pay the claim on the GC's behalf — because the damage occurred during ongoing operations and was caused by the sub's work. This is exactly the protection CG 20 10 is designed to provide.

CG 20 37: Additional Insured — Completed Operations

CG 20 37, formally titled "Additional Insured — Owners, Lessees or Contractors — Completed Operations," extends additional insured coverage to claims arising after the named insured's work is finished.

The key characteristics of CG 20 37 include:

Scope — Covers claims arising from the named insured's completed work
Time trigger — The bodily injury or property damage must occur after the named insured's work is complete
Causation requirement — Same "caused in whole or in part by" language as CG 20 10 04 13
Duration — Coverage applies for the remainder of the policy period after work is completed, and can extend into renewal periods if the endorsement is maintained
Products/Completed Operations aggregate — Claims under CG 20 37 erode the Products/Completed Operations aggregate, not the General Aggregate

CG 20 37 is the endorsement that protects you from the claims you cannot see coming — the ones that emerge months or years after the work is done. Construction defect claims, latent moisture damage, structural failures, and injuries from improperly installed systems all fall into this category.

What CG 20 37 Covers: An Example

Using the same plumbing scenario, suppose the sub completes their work and leaves the site. Eight months later, a concealed pipe joint fails, flooding the building. The building owner sues the GC.

If the GC has only CG 20 10 (ongoing operations), their additional insured coverage does not apply because the work was completed. The GC must rely entirely on their own insurance and indemnification rights against the sub.

If the GC also has CG 20 37 (completed operations), their additional insured coverage remains active for claims arising from the sub's completed work. The sub's insurer must defend the GC, even though the sub finished the job months ago.

Why You Need Both Endorsements

The gap between CG 20 10 and CG 20 37 is not a technicality — it is a coverage chasm that swallows claims regularly. Consider the timeline of a typical construction project:

Months 1-12: Subcontractor performs work (CG 20 10 applies)
Month 12: Subcontractor completes scope and demobilizes (CG 20 10 stops applying)
Months 13-120: Statute of repose period during which defect claims can emerge (only CG 20 37 applies)

The math is clear. On a 12-month construction project in a state with a 10-year statute of repose, CG 20 10 covers 12 months and CG 20 37 covers up to 108 months. The longer coverage window is where the high-severity claims live.

Despite this, CG 20 37 is the most commonly omitted endorsement in construction COI programs. Reasons include:

Subcontractors' agents may not include it unless specifically requested
The COI may reference "Additional Insured" without specifying which endorsement forms
Operations teams checking COIs may not know to look for both form numbers
CG 20 37 may carry an additional premium, and cost-conscious subcontractors skip it

Any contract that requires Additional Insured status should explicitly require both CG 20 10 and CG 20 37, referenced by form number. Your COI compliance checklist should verify both.

How to Verify Additional Insured Status on a COI

Verifying additional insured status is a multi-step process that goes beyond simply looking for the words "Additional Insured" on the certificate.

Check the Description of Operations — Look for language such as "Certificate Holder is included as Additional Insured" or "Additional Insured per CG 20 10 and CG 20 37." The specific form numbers should be referenced.
Note the endorsement form numbers — CG 20 10 for ongoing, CG 20 37 for completed operations. Some insurers use proprietary endorsement forms instead of the standard ISO forms. If the form number is not CG 20 10 or CG 20 37, request a copy of the endorsement to verify the scope is equivalent.
Request the actual endorsement pages — The COI is not proof of coverage. Only the endorsement document, attached to the policy, confirms that (a) the endorsement exists, (b) your entity is named correctly in the schedule, and (c) the coverage terms match your requirements.
Verify entity name precision — Your exact legal entity name must appear on the endorsement schedule. "ABC Properties" and "ABC Properties LLC" are legally distinct entities. A mismatch could void your coverage.
Check the edition date — The edition date (e.g., 04 13, 07 04) determines the scope of coverage. Earlier editions are generally broader. Know which edition your contract requires and verify it on the endorsement.
Confirm the policy is active — An endorsement on an expired policy provides no coverage. Cross-reference the endorsement with the policy dates on the COI.

Automated tools like unifi.ai can detect endorsement form numbers on COIs, flag the CG 20 10/CG 20 37 gap automatically, and alert you when additional insured language is missing. This replaces the manual line-by-line review that most operations teams currently perform. Check our pricing page for details.

Common Mistakes with Additional Insured Endorsements

Mistake 1: Assuming the COI creates coverage. The ACORD 25 certificate explicitly states it "is issued as a matter of information only and confers no rights upon the certificate holder." If the endorsement was never actually added to the policy, the COI language is meaningless.

Mistake 2: Accepting blanket additional insured language without verification. Some policies include "blanket additional insured" provisions that automatically extend coverage to any party required by written contract. While convenient, blanket endorsements may have narrower terms than the standard CG 20 10/CG 20 37. Always verify the actual endorsement wording.

Mistake 3: Not requiring additional insured on the umbrella/excess policy. Your contract may require $5M in additional insured coverage. The sub's CGL has a $1M per-occurrence limit. Without additional insured status on the umbrella as well, your protection caps at $1M — far below your contractual requirement.

Mistake 4: Ignoring the products/completed operations aggregate. CG 20 37 claims erode the Products/Completed Operations aggregate. If the sub has a $2M aggregate and multiple projects, claims from other jobs could deplete the aggregate before your claim is paid. Per-project aggregate endorsements (CG 25 03) mitigate this risk.

Mistake 5: Failing to require ongoing maintenance of the endorsement. Additional insured endorsements only apply while the policy is in force. If the sub drops the endorsement at their next renewal, your completed operations coverage disappears. Contracts should require the sub to maintain additional insured coverage for a specified period after project completion.

Additional Insured vs. Other Coverage Extensions

Additional insured is often confused with other insurance concepts. Here is how they differ:

Additional Insured vs. Certificate Holder — A certificate holder is simply the entity that requested the COI. Being named as certificate holder confers no coverage rights. Being named as additional insured (via endorsement) confers coverage rights.

Additional Insured vs. Loss Payee — A loss payee is named on property insurance policies and has a right to receive insurance proceeds for property losses. Additional insured status applies to liability policies and provides defense and indemnification for third-party claims.

Additional Insured vs. Indemnification — A contractual indemnification clause requires the vendor to reimburse you for losses. Additional insured status gives you direct access to the vendor's insurance policy. Both are important — indemnification is only as good as the vendor's ability to pay, while additional insured status is backed by the insurance company's financial strength.

Frequently Asked Questions

Does additional insured status cover my own negligence?

Under the current CG 20 10 04 13 and CG 20 37 04 13 editions, coverage applies to liability "caused, in whole or in part," by the named insured's acts or omissions. This means if the claim involves shared fault, the additional insured still has coverage for the portion of liability attributable to the named insured. However, if the claim arises solely from the additional insured's own negligence with no connection to the named insured's work, the endorsement does not apply.

Can I be an additional insured on a Workers Compensation policy?

No. Workers Compensation policies do not have additional insured endorsements. The equivalent protection is a Waiver of Subrogation endorsement (WC 00 03 13), which prevents the insurer from seeking recovery from you after paying a workers comp claim to the named insured's employee.

What if the subcontractor uses a non-ISO additional insured endorsement?

Many insurers use proprietary endorsement forms that serve a similar function to CG 20 10 and CG 20 37. If you receive a non-ISO form number, request a copy of the endorsement and review the specific language. Key provisions to verify include: the scope of coverage (ongoing and/or completed operations), the causation requirement, and whether the additional insured schedule names your entity correctly. If the proprietary endorsement is narrower than the ISO standard, flag it as a compliance deficiency.

How long does completed operations additional insured coverage last?

CG 20 37 coverage lasts for the remainder of the policy period in which the work is completed, and continues into subsequent renewal periods as long as the endorsement is maintained. If the named insured drops the endorsement at renewal, coverage for future claims from completed operations is lost. Contracts should specify the number of years after project completion that the named insured must maintain completed operations additional insured coverage — typically matching the applicable statute of repose.

Is "Additional Insured where required by written contract" sufficient?

This blanket language is common in the Description of Operations section of COIs. It means the policy includes a blanket additional insured endorsement that automatically applies when required by a written contract. While this is generally acceptable, you should still request the actual endorsement to verify the specific terms. Some blanket endorsements have limitations (e.g., lower sub-limits, exclusions for certain project types, or no completed operations coverage) that may not meet your contract requirements.

Additional insured endorsements are the backbone of third-party risk transfer. Knowing the difference between CG 20 10 and CG 20 37 — and verifying both on every COI — protects your organization from the claims that hit hardest.

Try unifi.ai free — no signup required.