CG 20 10 is the most requested insurance endorsement in construction. GCs require it from every sub, and owners require it from every GC. Yet most compliance teams still accept COIs without confirming the endorsement is actually attached. Here’s what CG 20 10 is, what it covers, what it doesn’t, and how to verify your subs have it.
Maybe you’ve sent a subcontractor a contract that says “provide Additional Insured status via CG 20 10 endorsement,” then accepted their COI without checking whether the endorsement was attached. If so, you accepted a false sense of security in place of real risk transfer.
CG 20 10 is not automatically part of a general liability policy. It has to be added as an endorsement. A COI that lists you as certificate holder does not make you an additional insured. Only the endorsement does that.
What Is CG 20 10?
CG 20 10 is an ISO (Insurance Services Office) standard endorsement officially titled “Additional Insured: Owners, Lessees or Contractors, Scheduled Person or Organization.” It attaches to a subcontractor’s Commercial General Liability (CGL) policy and adds the general contractor, property owner or developer as an additional insured on that policy.
There are several editions. The current one is CG 20 10 04 13 (April 2013). Older editions, 10/01 and 07/04, have different coverage scopes, and the 04/13 edition narrows coverage in ways that matter for GCs. Always check the edition date when you review an endorsement.
Quick definition: As an additional insured under CG 20 10, the GC or owner gets limited coverage under the sub’s GL policy for certain claims arising from the sub’s work during ongoing operations. That protection ends when the sub’s work is complete, which is why CG 20 37 is required separately for completed operations.
What CG 20 10 Covers, and What It Doesn’t
What it covers
Third-party bodily injury and property damage claims arising from the sub’s ongoing operations, where both the sub and the GC may be liable.
What it doesn’t cover
The GC’s sole negligence. Claims after the sub’s work is complete. Professional or design errors. Claims above the sub’s policy limits.
Key limits of the CG 20 10 04/13 edition
- Ongoing operations only. Coverage ends when the sub’s work on the project is complete. For protection after that, you need CG 20 37, so require the two together.
- Proportional liability. The 04/13 edition only responds when the sub is at least partly at fault. If the GC is 100% responsible for a loss, the sub’s policy may not pay.
- No coverage for the GC’s sole negligence. A subcontractor can’t insure the GC against the GC’s own mistakes.
- State variations. Some states limit or prohibit certain indemnity provisions, which can change how CG 20 10 applies. Confirm your requirements are enforceable where the project is.
The 04/13 edition gap: When ISO moved from the 07/04 edition to 04/13, it narrowed coverage in ways that surprise many GCs. If your contract just says “provide CG 20 10” without an edition, a sub who submits the 04/13 form is technically compliant, even though older editions gave you broader protection. Review your contract language and consider naming the edition or requiring equivalent broader wording.
Blanket vs. Scheduled Additional Insured: The Difference That Matters
A sub’s policy can give you additional insured status in two ways: scheduled or blanket.
| Type | How it works | GC’s risk |
|---|---|---|
| Scheduled | Your company name is listed on the endorsement form. Coverage is unambiguous. | Lower Clear documentation |
| Blanket | Covers anyone the sub is required by written contract to add as an additional insured. You aren’t named. | Medium Depends on contract language |
| No endorsement | The COI lists you as certificate holder only. No additional insured status, whatever the COI implies. | High No actual coverage |
Blanket endorsements are widely accepted, but only when the written contract clearly requires additional insured status and the blanket wording is triggered by that contract. Billy’s AI Review Assistant checks whether the blanket language actually works for your contract setup, not just whether it appears on the document.
How to Verify a Sub Actually Has CG 20 10
This is where most GCs fall short. Ticking “AI endorsement: yes” on a COI checklist is not verification. Real verification looks like this:
- Request the endorsement, not just the COI. The ACORD 25 shows that an additional insured endorsement exists. To check the form number, edition date and wording, you need the endorsement itself.
- Confirm the form number. Look for CG 20 10, or a non-ISO form with equivalent coverage. “Additional insured per written contract” typed on the COI is not enough.
- Check the edition date. 04/13 is current. Compare it with what your contract requires.
- Confirm blanket or scheduled. If blanket, make sure your contract triggers it. If scheduled, make sure your exact legal entity is listed, not a DBA or a related company.
- Verify completed operations separately. CG 20 10 only covers ongoing operations. If your contracts require completed operations coverage, and for most scopes they should, you also need CG 20 37.
How Billy handles this automatically: Billy’s AI Review Assistant reads every submitted COI and endorsement against your contract requirements. It confirms CG 20 10 is present, checks the edition date, identifies blanket or scheduled wording, and flags whether CG 20 37 is also needed. A trained reviewer spends 20 to 30 minutes per vendor on this. Billy does it in under 10 seconds.
5 Common Mistakes GCs Make With CG 20 10
1. Accepting a COI without the actual endorsement
The COI is a summary, not the endorsement. An “AI endorsement” checkbox on the COI doesn’t prove CG 20 10 is attached to the policy. Always require the endorsement form along with the certificate of insurance.
2. Not requiring CG 20 37 alongside CG 20 10
CG 20 10 covers ongoing operations. Once your sub finishes and leaves the site, that coverage ends. A roof leak six months later or a structural problem found during occupancy falls under completed operations, which needs CG 20 37. Most GCs require both. Many forget to check that both are actually there.
3. Not specifying primary and non-contributory
Even with CG 20 10 in place, the sub’s policy may not pay first if your own GL policy also responds. Primary and non-contributory wording makes the sub’s policy pay first, which is almost certainly what your contract intends. Require it explicitly and verify it separately from the additional insured endorsement.
4. Not updating requirements when contracts change
If your standard contract names a specific CG 20 10 edition and ISO has since released a newer one, your requirements may not match what subs submit. Review your contract templates with your broker or risk manager on a regular schedule.
5. Treating the initial COI as a permanent record
COIs expire, and endorsements expire with the policies they’re attached to. A sub who was fully compliant in January may not be in October. COI tracking at scale means monitoring compliance continuously, not just at onboarding.
If you manage more than a few dozen subs, construction compliance tracking software can watch every policy and endorsement for expirations and changes, so you aren’t relying on a spreadsheet reminder.
Stop accepting COIs without verifying endorsements
Billy’s AI Review Assistant checks CG 20 10, CG 20 37, primary and non-contributory, and waiver of subrogation on every submitted document, automatically and in seconds.
See how it worksFrequently Asked Questions
Does CG 20 10 cost extra to add to a GL policy?
Usually very little, often $0 to $100 a year. It’s a standard endorsement most carriers add at little or no cost. If a sub says they can’t provide CG 20 10, look into why.
What’s the difference between CG 20 10 and CG 20 26?
CG 20 26 is an older additional insured endorsement for ongoing operations. CG 20 10 has replaced it in most situations and gives similar, though not identical, coverage. If a sub submits CG 20 26, review it with your broker before accepting it as equivalent.
Can a blanket AI endorsement replace a scheduled one?
In most cases, yes, as long as your written contract clearly requires additional insured status and the blanket wording is triggered by that contract. The risk is that coverage depends on the contract. If there’s a dispute about whether the agreement exists or covers the right scope, coverage can be contested.
What happens if a sub doesn’t have CG 20 10 and a claim happens?
Without additional insured status, you can’t tender the claim to the sub’s insurer. You’re left with your own policy, which likely has a higher deductible and may lead to higher premiums. That’s why verifying endorsements, not just collecting COIs, is the foundation of real risk transfer in construction.
