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

Last updated July 2026.

CG 20 10 and CG 20 37 are the two ISO additional insured endorsement forms construction contracts ask for most. CG 20 10 grants additional insured status for the vendor's ongoing operations, the work while it is being performed. CG 20 37 grants it for completed operations, the finished work after the crew leaves. They cover different phases of the same project, which is why well written contracts require both.

If you review certificates of insurance for a general contractor, a developer or a property owner, these two form numbers show up in the description of operations box constantly, and the difference between them decides whether you are actually protected after a project closes out. Here is what each one does, when you need both, and how to confirm they are real rather than typed onto a certificate.

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

CG 20 10 adds you as an additional insured for the named vendor's ongoing operations, meaning liability arising while the work is still underway. CG 20 37 adds you for completed operations, meaning liability that surfaces after the work is finished and handed over. A slip during framing is ongoing operations. A framing defect that causes a collapse two years later is completed operations. One form does not cover the other, so many injuries and property claims fall into a gap if only one is attached.

What is CG 20 10?

CG 20 10 is the ISO endorsement titled Additional Insured, Owners, Lessees or Contractors, Scheduled Person or Organization. It extends the named insured's general liability coverage to the person or organization listed, for liability caused in whole or in part by the named insured's ongoing operations. On a subcontractor's policy, it is what makes the general contractor and the owner additional insureds while the subcontractor is on site working.

What is CG 20 37?

CG 20 37 is the companion endorsement, Additional Insured, Owners, Lessees or Contractors, Completed Operations. It extends the same additional insured status to liability arising out of the work after it is put to its intended use. Construction defects rarely appear during the job. They appear months or years later, which is exactly the window CG 20 37 covers and CG 20 10 does not.

Do I need both CG 20 10 and CG 20 37?

Yes, on construction work you almost always need both. CG 20 10 protects you during the project and CG 20 37 protects you after it, and construction claims routinely arrive years after completion when only the completed operations form responds. A contract that requires additional insured status for ongoing and completed operations, or names both form numbers, is asking for the pair. Requiring only CG 20 10 leaves the long tail of defect claims uncovered.

What does the CG 20 10 04 13 edition change?

The 04 13 edition of CG 20 10 narrows coverage in two ways worth catching. It limits additional insured coverage to the extent permitted by law and to the coverage required by the contract, and it explicitly excludes completed operations. That completed operations exclusion is the main reason CG 20 37 has to be attached separately. If a subcontractor gives you only a 04 13 edition CG 20 10 and no CG 20 37, your completed operations protection is missing even though a form number is present.

Is CG 20 10 blanket or scheduled?

The standard CG 20 10 is a scheduled form, meaning it names the specific additional insured in a schedule on the endorsement. Blanket additional insured coverage is provided by different forms or by policy wording that grants status to anyone the named insured has agreed in a written contract to add, such as CG 20 33 or CG 20 38 for ongoing operations. Blanket wording is convenient, but you still need to confirm it actually reaches completed operations, since many blanket forms cover only ongoing work. The blanket versus scheduled distinction is separate from the ongoing versus completed operations distinction, and both matter.

How do I verify CG 20 10 and CG 20 37 on a certificate of insurance?

The certificate itself is not proof. The description of operations box on an ACORD 25 may say additional insured per CG 20 10 and CG 20 37, but that text is typed by whoever issued the certificate and is not the policy. To verify, request copies of the actual endorsements and confirm the form numbers, the edition dates, the named insured and that you or your entity are covered, whether by schedule or by qualifying blanket language. If you are digitizing a backlog of paper endorsements to check them at scale, you can pull the key fields out of each document automatically rather than reading every page by hand. For a walkthrough of the rest of the form, see how to read a certificate of insurance.

Track the endorsements, not just the certificate

Most COI programs fail not because they miss the certificate but because they never confirm the endorsements behind it. Requiring CG 20 10 and CG 20 37 in your contracts is step one. Confirming both endorsements are actually attached, current and correct on every renewal is the ongoing work, and it is what separates a real compliance program from a folder of PDFs. That is the job COI tracking for general contractors is built for: it reads each ACORD 25, checks your required coverages and endorsement wording automatically, and flags a subcontractor whose completed operations coverage is missing before they set foot on site. Teams running compliance through Procore can do the same with COI tracking for Procore.

For the wider context, completed operations coverage has its own guide in what is completed operations coverage, and the difference between being an additional insured and a certificate holder is covered in additional insured vs certificate holder.