What is a CG 20 10 Endorsement?
The CG 20 10 is the most widely requested Additional Insured endorsement in the construction industry. This guide covers what it is, which ISO editions matter, when it applies, and how to verify it automatically.
The CG 20 10 is an official form drafted by the Insurance Services Office (ISO) that modifies a commercial general liability policy. It grants "Additional Insured" status to a third party (such as a general contractor or project owner) for liability caused by the named insured's (the subcontractor's) ongoing operations.
ISO Edition History: Why the Date on the Form Matters
The CG 20 10 has been revised multiple times by ISO. Each edition changes the scope of coverage extended to the additional insured. The three editions general contractors encounter most often are:
The original broad form. Provided virtually unlimited additional insured coverage for any liability "arising out of" the named insured's work, with no requirement to prove the named insured was at fault. ISO discontinued this edition in 2004.
Retained the "arising out of" trigger language but added a limitation requiring that the additional insured's coverage be linked to the named insured's ongoing operations. Most construction attorneys consider this the preferred edition because it still offers broad protection.
Replaced "arising out of" with "caused, in whole or in part, by" the named insured's acts or omissions. This tighter language means the additional insured must demonstrate the named insured bears at least partial fault, which can complicate claims defense.
Always verify the edition date on the endorsement form. A CG 20 10 04 13 provides meaningfully narrower coverage than a CG 20 10 07 04. If your subcontract specifies the 07 04 edition, do not accept a 04 13 substitute without legal review.
When the CG 20 10 Applies and Who Requires It
The CG 20 10 is required whenever a hiring party needs Additional Insured protection while a subcontractor is physically performing work. Common scenarios include:
- General contractors hiring trade subcontractors — the GC requires the sub to name them as additional insured for ongoing operations on the jobsite.
- Project owners and developers — often named as additional insured on both the GC's and the sub's policies.
- Property managers — require vendors (HVAC, janitorial, landscaping) to add them as additional insured during active service periods.
- Lenders and investors — construction loan agreements frequently mandate additional insured status on the borrower's CGL policy.
The CG 20 10 covers only ongoing operations. Once the subcontractor finishes their scope and leaves the site, the CG 20 10 coverage terminates. For post-completion protection, the general contractor must also require a CG 20 37 (Completed Operations) endorsement. For a detailed comparison, see our guide: CG 20 10 vs CG 20 37 Endorsements Explained.
Worked Example: Why a GC Requires the CG 20 10
A general contractor, Ridgeline Builders, hires a framing subcontractor, Apex Framing LLC, for a 200-unit multifamily project. Ridgeline's subcontract requires Apex to carry $1M/$2M General Liability with CG 20 10 07 04 naming Ridgeline as Additional Insured.
Why CG 20 10 07 04 specifically?Three months into framing, an Apex worker drops a beam that injures a concrete finisher employed by a different sub. The concrete sub's employer sues Ridgeline as the GC controlling the jobsite. Because Apex provided the CG 20 10 07 04 endorsement, Ridgeline tenders the claim to Apex's insurer. The "arising out of" language in the 07 04 edition requires only that the injury arose from Apex's operations — Ridgeline does not need to prove Apex was specifically negligent.
Had Ridgeline accepted the 04 13 edition instead, the insurer could argue that Ridgeline must prove Apex's acts or omissions "caused, in whole or in part" the injury — a higher bar that introduces litigation risk and potential coverage gaps.
How SubDoc Detects and Verifies the CG 20 10
Manually checking thousands of PDFs to verify that the CG 20 10 form is present, correctly scheduled, and using the right edition is an administrative nightmare. SubDoc automates this process:
- ADDL INSD column check: SubDoc's AI OCR reads the ACORD 25 coverage grid and flags any policy line where the ADDL INSD column is not marked "Y."
- Endorsement form detection: The AI scans all attached PDF pages for the CG 20 10 form header, identifying both the form number and the edition date (07 04 vs 04 13).
- Schedule verification: Confirms that the additional insured name on the endorsement matches the certificate holder or project entity on file.
- Deficiency alerts: If the CG 20 10 is missing or the wrong edition is attached, SubDoc automatically sends a deficiency notification to the subcontractor and their broker with specific remediation instructions.
This eliminates the two most common verification failures: accepting a certificate where the broker typed "Additional Insured" in the Description of Operations box without attaching the actual endorsement form, and accepting the wrong edition without realizing the coverage scope was narrowed.
Common Mistakes with the CG 20 10
- Accepting the ACORD 25 without the endorsement schedule. The certificate itself is not the endorsement. You need the actual CG 20 10 form page attached to the policy documents.
- Not verifying the edition date. A CG 20 10 04 13 may look identical to a 07 04 at first glance, but the legal coverage scope differs significantly.
- Confusing CG 20 10 with CG 20 37. The CG 20 10 covers ongoing operations only. Once work is finished, you need a CG 20 37 for completed operations coverage.
- Accepting carrier-specific manuscript forms. Some insurers issue their own "Additional Insured — Ongoing Operations" forms that look similar but may contain exclusions or limitations not present in the standard ISO CG 20 10. Always verify the ISO form number.
- Not requiring CG 20 10 alongside Primary and Non-Contributory wording. Even with Additional Insured status, the subcontractor's insurer may try to split claim costs with the GC's insurer unless PNC wording is also endorsed.
Related Glossary Terms
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