Last updated: September 24, 2026. Clause mechanics verified September 2026 — the wording on your exhibit governs; read the endorsement, not the certificate.
On a subcontract, "additional insured" means the general contractor is added as an insured party under your general liability policy, so your insurer defends and pays for claims arising from your work before the GC's own policy responds. This is only real if your policy carries an additional insured endorsement (typically CG 20 10 for ongoing work and CG 20 37 for completed operations). A certificate of insurance naming the GC as certificate holder does not grant additional insured status; the certificate is a receipt, the endorsement is the coverage.
TL;DR
- "Additional insured" = the GC gets covered under your policy, not just notified. Notification is the certificate holder's job.
- The endorsement is the thing that matters. Look for CG 20 10 (ongoing operations) and CG 20 37 (completed operations). Both, not one, if the exhibit asks for completed ops.
- The certificate of insurance (COI) is evidence, not coverage. A COI can say "additional insured" in a box and still be backed by zero endorsement. That gap is where GCs get burned and payment gets withheld.
- These mechanics are national. What "additional insured" means is identical in all 50 states. Only licensing, workers' comp thresholds and privacy statutes vary by state.
Definition: what additional insured actually means on a subcontract
Additional insured is a status added to your commercial general liability (CGL) policy by endorsement, extending your policy's defense and indemnity to a named third party, usually the general contractor and often the project owner, for liability arising out of your work. When a GC is an additional insured on your policy, and something on the job goes wrong that traces to your scope, your insurer steps in for the GC as if the GC were you. That is the whole point: the GC is pushing the risk of your work onto your policy, in the correct order, before its own coverage is touched.
Two words control how far that extension reaches: ongoing operations and completed operations. Ongoing means while you are actively performing. Completed operations means after you have finished and left the site, which is when a lot of construction claims actually surface. If your endorsement only covers ongoing operations and the exhibit demanded completed operations too, you are short, and a careful GC's risk team will bounce your paperwork.
Why "additional insured" trips up subs at signing
The confusion is not stupidity. It is that three separate documents use overlapping language and only one of them is coverage.
The exhibit says "Contractor shall be named as an additional insured." The broker sends a certificate with the GC listed and the additional insured box checked. Everyone assumes the loop is closed. It is not, because the certificate is a summary of coverage that carries an explicit disclaimer: it confers no rights on the holder and does not amend, extend or alter the underlying policy. The ACORD 25 form — the standard certificate used across the industry — states this in its own footer. That means the "additional insured" checkbox on a COI is a representation, not a grant. The grant lives in the endorsement attached to the policy.
So the sub who wants to get paid, and the GC who wants to be actually protected, need to look past the certificate to two things:
- Which endorsement form is attached (CG 20 10, CG 20 37, or a broader manuscript/blanket form).
- What that form's edition date says, because ISO has revised these forms over the years and older editions cover more or less than newer ones. The edition date is printed on the form, e.g., "CG 20 10 04 13."
CG 20 10 vs. CG 20 37: reading the endorsement
These are the two Insurance Services Office (ISO) standard forms most subcontracts reference, either by number or by describing what they do.
- CG 20 10 — Additional Insured, Owners, Lessees or Contractors (Scheduled Person or Organization). This covers the additional insured for liability arising out of your ongoing operations performed for that party. Once your work is complete, this form generally stops responding.
- CG 20 37 — Additional Insured, Owners, Lessees or Contractors (Completed Operations). This picks up where CG 20 10 leaves off, covering liability arising out of your completed operations — the claims that surface after you have finished and demobilized.
If the exhibit demands completed operations coverage — and most well-drafted construction exhibits do — a CG 20 10 alone is not enough. You need both forms, or a blanket endorsement that explicitly reaches ongoing and completed operations. Blanket forms (such as a CG 20 33 combined with completed-ops language, or a carrier's proprietary blanket) can satisfy both, but only if the wording actually says so. Do not assume "blanket" means "everything."
A note on edition dates: the widely used 04 13 editions of CG 20 10 and CG 20 37 tie the additional insured's coverage to the extent permitted by law and, importantly, condition coverage on the terms of your written contract. Earlier editions (like 10 01 or 07 04) behave differently on issues such as whether coverage extends to the additional insured's sole negligence. When a GC's risk manager specifies an edition date, they mean it — supplying a different edition is a common reason paperwork gets rejected.
The COI is evidence, not coverage
Say it plainly: a certificate of insurance proves that a policy exists and summarizes some of its features on the day it was issued. It does not create coverage, it does not bind the insurer to the additional insured, and it can be out of date the moment a policy is canceled or amended.
The failure pattern looks like this:
- The subcontract exhibit requires additional insured status, ongoing and completed operations, with a specific edition date.
- The broker issues a COI with the box checked and moves on.
- No endorsement is actually attached, or the wrong edition is attached.
- A claim surfaces months after the work is done. The carrier reviews the policy, finds no completed-operations endorsement, and declines to defend the GC.
- The GC's own carrier now foots the bill and subrogates — or the GC withholds final payment and retention from the sub.
The fix is not complicated, it just requires actually reading the policy documents: request a copy of the endorsement itself, confirm the form number and edition date, and confirm it names the GC (and owner, if required) or is a valid blanket form triggered by your written contract. The certificate is where you start; the endorsement is where you finish.
Are these mechanics the same in every state?
Yes — with narrow, well-defined exceptions. The meaning of "additional insured," the function of CG 20 10 and CG 20 37, and the distinction between a certificate and an endorsement are national. ISO forms are used across the country, and a completed-operations endorsement means the same thing in Texas as it does in Ohio.
What actually varies by state:
- Anti-indemnity statutes. Many states restrict or void contract provisions that require a sub to indemnify a GC for the GC's own negligence. These statutes can also limit how far additional insured coverage reaches, particularly for the additional insured's sole fault. This is why the 04 13 editions include "to the extent permitted by law" language.
- Workers' compensation thresholds. Whether and when workers' comp is mandatory, and the exemptions for small employers or sole proprietors, differ by state — but this is separate from your CGL additional insured obligation.
- Contractor licensing. Licensing classifications, bonding and registration requirements are state (and sometimes local) matters.
- Privacy and notice statutes. Some states impose specific cancellation-notice rules on carriers and certificate holders.
None of those change what "additional insured" means. They change the enforceability of certain indemnity clauses and the surrounding compliance obligations. Read the endorsement for the coverage; read your state's anti-indemnity statute for the limits on how far a GC can push risk onto you.
Authoritative references
- National Association of Insurance Commissioners (NAIC), Commercial General Liability consumer and regulator guidance — content.naic.org (accessed September 2026).
- Insurance Services Office (ISO) / Verisk, standard commercial lines forms including CG 20 10 and CG 20 37 — verisk.com/insurance/products/iso-forms (accessed September 2026).
- International Risk Management Institute (IRMI), Additional Insured Endorsements reference — irmi.com (accessed September 2026).
Bottom line
On a subcontract, being "additional insured" is a real transfer of risk onto your CGL policy — but only when the correct endorsement is attached. Confirm the form (CG 20 10 for ongoing, CG 20 37 for completed operations, or a valid blanket), confirm the edition date, and treat the certificate as a receipt rather than proof of coverage. The mechanics are national; the indemnity limits and compliance rules are where your state comes in.
{
"@context": "https://schema.org",
"@type": "FAQPage",
"mainEntity": [
{
"@type": "Question",
"name": "What does \"additional insured\" mean on a subcontract?",
"acceptedAnswer": {
"@type": "Answer",
"text": "It means the general contractor is added as an insured party under your commercial general liability policy by endorsement, so your insurer defends and pays for claims arising out of your work before the GC's own policy responds. It is only effective if your policy carries an additional insured endorsement, typically CG 20 10 for ongoing operations and CG 20 37 for completed operations."
}
},
{
"@type": "Question",
"name": "Does a certificate of insurance grant additional insured status?",
"acceptedAnswer": {
"@type": "Answer",
"text": "No. A certificate of insurance (such as ACORD 25) is a summary of coverage and carries a disclaimer stating it confers no rights and does not amend the policy. Even if the additional insured box is checked, the actual coverage comes only from the endorsement attached to the policy. The certificate is evidence; the endorsement is the coverage."
}
},
{
"@type": "Question",
"name": "What is the difference between CG 20 10 and CG 20 37?",
"acceptedAnswer": {
"@type": "Answer",
"text": "CG 20 10 covers the additional insured for liability arising out of your ongoing operations while you are actively performing. CG 20 37 covers your completed operations after the work is finished. If a subcontract exhibit requires completed operations coverage, CG 20 10 alone is not enough; you need both forms or a valid blanket endorsement that reaches both."
}
},
{
"@type": "Question",
"name": "Are additional insured mechanics the same in every U.S. state?",
"acceptedAnswer": {
"@type": "Answer",
"text": "Yes, the meaning of additional insured and the function of CG 20 10 and CG 20 37 are national. What varies by state are anti-indemnity statutes that limit how far risk can be transferred, workers' compensation thresholds, contractor licensing, and cancellation-notice rules."
}
}
]
}