Written by Justin Goodman, CIC, CRIS, CCIP, CEO and Co-Founder, Total CSR Published: August 26, 2026 · Last reviewed: August 26, 2026
In plain language: CG 20 10 is an insurance form that adds a property owner, developer, or general contractor as a protected party on a contractor’s or subcontractor’s liability policy. It covers claims tied to work still in progress, so the added party shares the contractor’s liability protection while the job is active.
Technical definition: CG 20 10 is an ISO endorsement to a commercial general liability policy that grants additional insured status for bodily injury, property damage, or personal injury liability arising from the named insured’s ongoing operations performed for the additional insured, subject to the contract triggering the endorsement.
CG 20 10 Endorsement at a Glance
Key attributes of the CG 20 10 endorsement are summarized below for quick reference.
| Attribute | Detail |
|---|---|
| Also known as | Additional Insured – Owners, Lessees or Contractors (Form B) |
| Category | Liability policy endorsement |
| Lines of business | Commercial General Liability |
| Industries most affected | Construction, real estate development, property management |
| Related forms or endorsements | CG 20 37 (completed operations), CG 20 33 (blanket, primary and noncontributory), CG 20 38 |
| Who bears the risk | Named insured (contractor/subcontractor) extends protection to additional insured (owner/GC) |
| Common solution | Pairing CG 20 10 with CG 20 37 for full project-to-completion coverage |
| Also interacts with | Certificates of insurance, indemnification clauses, primary and noncontributory wording |
Key Takeaways
- CG 20 10 adds a property owner, developer, or general contractor as an additional insured on a contractor’s CGL policy for liability tied to work in progress.
- Agencies rely on this endorsement daily to satisfy construction contract insurance requirements before a subcontractor can start a job.
- The most common pitfall is assuming CG 20 10 alone covers claims after the job is finished, when only the 07 04 edition with completed operations wording, or a paired CG 20 37, does that.
- A quick win is confirming the endorsement edition date on the policy itself, not just the certificate of insurance, since certificates do not alter coverage.
What Is CG 20 10 Endorsement in Insurance?
CG 20 10 is the ISO endorsement construction contracts most often require to make an owner, developer, or general contractor an additional insured under a subcontractor’s or contractor’s commercial general liability policy. It exists because indemnification agreements alone leave the upstream party dependent on the downstream party’s financial ability to pay a claim. Adding the upstream party as an additional insured gives them direct access to the named insured’s liability policy and its defense obligation, shifting risk transfer from a contractual promise to an actual insurance asset.
The doctrine behind this is straightforward risk transfer: the party with less control over jobsite activity, typically the owner or GC, wants coverage that responds even if the subcontractor’s indemnification clause is unenforceable under state anti-indemnity statutes. Many states, including Texas and California, restrict or void broad-form indemnification, so additional insured status through CG 20 10 becomes the more reliable mechanism.
A general contractor building a retail center requires its framing subcontractor to name it as an additional insured before framing begins. The subcontractor’s carrier issues CG 20 10, and a worker on the framing crew is later injured and sues the GC for negligent site oversight while the framing subcontractor’s crew was still actively working. Because the injury arose from the subcontractor’s ongoing operations, the GC has direct additional insured coverage under the subcontractor’s policy, separate from and in addition to the GC’s own CGL policy.
How Does CG 20 10 Endorsement Work?
- The contract requirement. A construction contract, lease, or service agreement requires the named insured to add another party as an additional insured for ongoing work.
- The endorsement issuance. The named insured’s carrier attaches CG 20 10 to the CGL policy, naming the additional insured and referencing the written contract that triggers it.
- The certificate delivery. The agency issues a certificate of insurance reflecting the endorsement, though the certificate itself carries no contractual weight and does not create coverage.
- The claim event. A third party is injured or property is damaged during the named insured’s ongoing operations performed for the additional insured.
- The coverage response. The additional insured tenders the claim under the named insured’s policy, and the carrier evaluates whether the injury arose from ongoing operations as the endorsement requires, then defends and indemnifies accordingly.
Real Claim Examples Involving CG 20 10 Endorsement
Scaffolding Collapse During Active Construction
A masonry subcontractor’s scaffolding collapses on a mixed-use development, injuring a pedestrian on the adjacent sidewalk. The general contractor, named as an additional insured on the mason’s policy through CG 20 10, is sued alongside the mason for inadequate site safety oversight. Because the injury occurred while the mason’s ongoing operations were active, the GC’s tender is accepted, and the mason’s carrier defends both parties under the same policy.
Injury Reported After Substantial Completion
A property owner is sued eighteen months after a roofing project finished when a leak causes water damage traced to defective installation. The owner attempts to tender the claim under the roofer’s CG 20 10 endorsement, but the carrier denies coverage because the standard ongoing operations form does not extend to completed operations claims. The owner’s own policy ultimately responds, exposing a gap the agency should have closed with CG 20 37 at binding.
Subcontractor Named on the Wrong Project
A subcontractor’s carrier issues CG 20 10 referencing a blanket contract endorsement rather than the specific jobsite named in the underlying agreement. When a dispute arises over which project the endorsement covers, the carrier initially disputes whether the additional insured’s claim falls within the endorsement’s scope. The agency’s documented contract on file resolves the ambiguity in the additional insured’s favor, illustrating why matching endorsement wording to actual contract language matters.
CG 20 10 Endorsement vs. CG 20 37: What Is the Difference?
CG 20 10 and CG 20 37 are companion ISO additional insured endorsements that together, not separately, provide full project lifecycle coverage. CG 20 10 covers ongoing operations only, while CG 20 37 extends additional insured status to completed operations claims that surface after the work is finished.
| Comparison area | CG 20 10 | CG 20 37 |
|---|---|---|
| Primary use case | Coverage while work is actively in progress | Coverage after the job is complete |
| Coverage / concept type | Ongoing operations additional insured endorsement | Completed operations additional insured endorsement |
| Typical exclusions | Claims arising after work is finished | Claims arising during active operations |
| Who is most affected by errors | Owners and GCs facing claims post-completion with no coverage | Subcontractors who assume one form covers both phases |
| Common mistakes | Treating it as sufficient for the full contract duration | Omitting it entirely, leaving a completed operations gap |
What Are the Most Common Mistakes With CG 20 10 Endorsement?
- Assuming the 2004 edition and later includes completed operations coverage, when only the 1985 edition offered broader completed operations language that ISO subsequently narrowed.
- Relying on a certificate of insurance as proof of coverage without confirming the actual endorsement is attached to the policy, since certificates are not contracts and create no coverage themselves.
- Failing to pair CG 20 10 with CG 20 37, leaving the additional insured uncovered for claims that surface after project completion.
- Naming the additional insured incorrectly or referencing the wrong contract, which can create a coverage dispute at the worst possible time, during an active claim.
- Overlooking primary and noncontributory requirements, since CG 20 10 alone does not make the additional insured’s coverage primary unless CG 20 01 or similar wording, or a blanket endorsement with that language, is also in place.
- Not confirming state-specific restrictions on additional insured scope, since several states limit how broadly additional insured status can extend regardless of endorsement wording.
How to Explain CG 20 10 Endorsement to a Client
Explaining CG 20 10 Endorsement to a personal lines client
This endorsement generally does not apply to personal lines policies, since it is a commercial general liability form used in business and construction contracts. If a personal lines client asks about it, it is usually because they are a landlord or homeowner working with a contractor who was asked to provide this coverage.
Explaining CG 20 10 Endorsement to a small business owner
This endorsement adds your client or business partner as a protected party on your liability policy while your crew is actively doing the work. It is often required before you can start a job, and it does not cost much to add, but the contract has to specifically require it and name the right party.
Explaining CG 20 10 Endorsement to a CFO or risk manager
CG 20 10 provides additional insured status for ongoing operations only, and it should be treated as one half of a complete risk transfer strategy alongside CG 20 37 for completed operations exposure. I would recommend confirming the specific edition date attached to each subcontractor’s policy, since coverage scope has changed across ISO revisions, and verifying primary and noncontributory language is present if your contracts require it.
Frequently Asked Questions About CG 20 10 Endorsement
What does CG 20 10 actually cover?
CG 20 10 covers bodily injury, property damage, and personal injury liability claims arising from the named insured’s ongoing operations performed for the additional insured under a written contract. It does not extend to claims arising after the named insured’s work on the project is complete unless a completed operations endorsement is also in place.
Does CG 20 10 cover completed operations claims?
Most current editions of CG 20 10 exclude completed operations claims, meaning coverage ends once the named insured’s work at the site is finished. Agencies typically pair CG 20 10 with CG 20 37 to close this gap for the full duration of potential liability exposure.
Is a certificate of insurance the same as the CG 20 10 endorsement?
A certificate of insurance is not the same as the endorsement and creates no coverage on its own. The certificate is only a snapshot of what the carrier reports as in force, so the agency should confirm the actual endorsement is issued and attached to the policy.
Can CG 20 10 make the additional insured’s coverage primary?
CG 20 10 by itself does not make the additional insured’s coverage primary and noncontributory over their own policy. That result requires additional endorsement language, often CG 20 01 or equivalent blanket wording, confirming the additional insured’s coverage is primary.
Why do contracts require CG 20 10 instead of just an indemnification clause?
Contracts require CG 20 10 because indemnification clauses depend on the indemnifying party’s financial ability to pay, and many states restrict or void broad indemnification agreements. Additional insured status gives the upstream party direct access to an actual insurance policy and its defense obligation, which is more reliable than a contractual promise alone.
Does the edition date of CG 20 10 matter?
The edition date matters significantly because ISO has revised the form’s scope multiple times, and older editions offered broader coverage than newer ones. Confirming the specific edition attached to a policy is a necessary step before relying on the endorsement to satisfy a contract requirement.
Related Insurance Terms
- CG 20 37 Endorsement: an ISO additional insured endorsement extending additional insured status to completed operations claims, typically paired with CG 20 10 for full project coverage.
- Additional Insured: a party added to another entity’s liability policy who receives coverage for claims arising from the named insured’s operations, the broader concept CG 20 10 implements.
- Completed Operations: the phase of liability exposure that begins once a contractor’s work is finished, which standard CG 20 10 forms typically exclude.
- Ongoing Operations: the phase of active work performance that CG 20 10 is specifically designed to cover.
- Certificate of Insurance: a document summarizing a policy’s coverage that does not itself create or alter coverage, often confused with proof that CG 20 10 is actually attached.
- Primary and Noncontributory Endorsement: wording that determines whether an additional insured’s coverage under CG 20 10 responds before or alongside the additional insured’s own policy.
Sources and References
- IRMI. Additional insured.
About the Author
Justin Goodman, CIC, CCIP, CISC, CLCS, CRIS, PCIA, QCLS, MFHR CEO and Co-Founder, Total CSR, Inc.
Justin Goodman is a third-generation insurance broker with over two decades in agency operations. He has trained more than 50,000 CSRs, account managers, and producers in commercial and personal lines coverage, from workers’ compensation to construction risk. He was named 2024 Insurance Journal Agent of the Year and one of the nation’s top five construction insurance experts by Risk & Insurance. He is the author of Retain, which applies cognitive science research on memory and knowledge transfer to insurance training, and speaks nationally on how agencies build durable technical expertise in their teams.