An additional insured endorsement is the form that actually extends a vendor policy to cover you. The certificate does not do it. The ADDL INSD checkbox on an ACORD 25 does not do it either. Only the endorsement attached to the policy grants the status, and which ISO form number the carrier used decides whether you are covered during the job, after it is finished, or not at all. This page lists the forms, states what each one grants, and shows how to check the one you were sent. Upload a certificate above and the AI reads the endorsement form numbers off the page.
Last updated August 2026
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The general liability additional insured forms you will actually be sent, with the official ISO title of each. Titles for every row except CG 20 39 and CG 20 40 were read directly from the ISO form documents. Those two were published in the December 2019 revision and are described here from insurance coverage counsel publications.
| Form | Official ISO title | Who it names | Completed operations |
|---|---|---|---|
| CG 20 10 | Additional Insured, Owners, Lessees or Contractors, Scheduled Person or Organization | A specific owner or general contractor the vendor performs operations for, written into the schedule by name | No, ongoing operations only from the 10 01 edition onward |
| CG 20 37 | Additional Insured, Owners, Lessees or Contractors, Completed Operations | The same scheduled party, after the work is finished and accepted | Yes, this is the form that provides it |
| CG 20 33 | Additional Insured, Owners, Lessees or Contractors, Automatic Status When Required In Construction Agreement With You | Anyone the vendor has a direct written construction agreement with, automatically | No |
| CG 20 38 | Additional Insured, Owners, Lessees or Contractors, Automatic Status For Other Parties When Required In Written Construction Agreement | Upstream parties the vendor has no direct contract with, such as the owner above your general contractor | No |
| CG 20 39 | Automatic status when required in written construction agreement with you, completed operations | Direct contracting parties, automatically, after completion. Added in the 12 19 revision | Yes |
| CG 20 40 | Automatic status for other parties when required in written construction agreement, completed operations | Upstream parties without direct privity, after completion. Added in the 12 19 revision | Yes |
| CG 20 26 | Additional Insured, Designated Person or Organization | Any designated party, with no requirement that they hired the vendor at all | No |
| CG 20 11 | Additional Insured, Managers or Lessors of Premises | A landlord or property manager, for the premises leased to the tenant | No |
| CG 20 15 | Additional Insured, Vendors | A distributor or retailer that sells the named insured product | Yes, for the scheduled product |
| CG 20 18 | Additional Insured, Mortgagee, Assignee or Receiver | A lender, assignee or receiver with an interest in the premises | No |
| CG 20 24 | Additional Insured, Owners or Other Interests From Whom Land Has Been Leased | A ground lessor, for liability arising out of the leased land | No |
| CG 20 32 | Additional Insured, Engineers, Architects or Surveyors Not Engaged by the Named Insured | A design professional working on the project but not hired by the vendor | No |
| CG 20 01 | Primary and Noncontributory, Other Insurance Condition | Not an additional insured form. It makes the vendor policy respond first, ahead of yours | Not applicable |
Almost every additional insured failure is discovered at claim time, because the document everyone files is the one document that cannot show the problem.
It is a box on a form, typed by whoever prepared the certificate. It records a claim that an endorsement exists. It is not the endorsement, it does not name the form number, and it does not show the edition date. A checked box and a missing endorsement look identical in your file.
From the October 2001 edition onward, CG 20 10 covers only ongoing operations. When the subcontractor finishes and a defect claim arrives eighteen months later, the additional insured has no coverage unless CG 20 37 or an equivalent was also attached. This is the most common gap in construction risk transfer and it is invisible on the certificate.
CG 20 33 and CG 20 38 grant status automatically, but only where a written construction agreement requires it. If the agreement is silent, verbal, or signed after the loss, the automatic grant may never attach. Blanket does not mean unconditional.
Since April 2013 the forms state that coverage will not be broader than the contract required, and that the insurer pays the lesser of the contract-required amount or the policy limits. A stale insurance clause in your template now caps your own coverage, no matter how much the vendor actually carries.
COISoftware extracts the form number and edition date off the endorsement page itself, checks them against the requirement recorded for that contract, and tells you which vendors are short.
The AI reads CG 20 10 04 13 off the endorsement and stores both parts as data. You can filter every vendor by which form they carry, which is impossible when the endorsements sit as PDFs in a shared drive.
A vendor with CG 20 10 and no CG 20 37, CG 20 39 or CG 20 40 is flagged as covered for ongoing operations only. That single check catches the most expensive failure in the category.
Set what each contract type requires once. Ongoing plus completed operations for construction, CG 20 11 for a lease, primary and non-contributory where your contract demands it. Every incoming endorsement is measured against that rule.
Carriers change editions quietly at renewal. A vendor who was on a broad form last year can come back on a narrower one and nothing in the certificate will say so. The comparison runs on every renewal automatically.
Form numbers are often buried in the Description of Operations box or on an attached ACORD 101 rather than on the endorsement itself. Those pages are read together, so a reference in the remarks schedule is not missed.
Non-compliant verdicts name the specific form. A request that says you need CG 20 37 or equivalent completed operations additional insured status gets resolved. One that says your certificate is non-compliant gets ignored.
Five checks, in the order that catches problems fastest.
A certificate with the ADDL INSD box ticked is not an endorsement. Ask for the endorsement pages attached to the policy. If the vendor cannot produce them, treat the status as unproven rather than as a paperwork delay.
Tip: Endorsement pages carry the header THIS ENDORSEMENT CHANGES THE POLICY. PLEASE READ IT CAREFULLY. A certificate never does.
The form number and edition date print together, in the format CG 20 10 04 13, on the same line as COMMERCIAL GENERAL LIABILITY. They repeat in the page footer next to the ISO copyright line. Both parts matter.
Tip: A form number starting CG 20 is an additional insured form. CG 24 and CG 25 are waiver and aggregate forms, not additional insured status.
If you see only CG 20 10, CG 20 33 or CG 20 38, coverage stops when the work is finished. You need CG 20 37 alongside a scheduled form, or CG 20 39 or CG 20 40 alongside a blanket one, to be covered for defect claims that surface after acceptance.
Tip: For construction work, the absence of a completed operations form is the finding worth chasing before anything else on the page.
On a scheduled form, read the schedule. It must name your legal entity, not a trade name, an affiliate or a property address. On a blanket form, confirm the written agreement that triggers automatic status exists and was signed before the work started.
Tip: Property owners with an entity per property fail this check constantly. The endorsement names the management company instead of the title-holding entity.
Additional insured status alone does not stop your own policy from contributing to a loss your vendor caused. CG 20 01 or equivalent wording is a separate form. If your contract requires primary and non-contributory coverage, that endorsement has to be in the packet too.
Tip: A contract that requires additional insured status but omits primary wording is a common template gap worth fixing once at the source.
Short answers to the comparisons people look up while a certificate is open in front of them.
CG 20 10 assumes the additional insured is a party the vendor performs operations for, such as a project owner or general contractor, and it covers only those operations at the scheduled location. CG 20 26 grants status to any designated person or organization with no requirement that they hired the vendor. That makes CG 20 26 the right form when the relationship is locational or regulatory rather than contractual, such as a municipality issuing a permit or a venue hosting a booth.
A scheduled form names you in a schedule printed on the endorsement. A blanket form, CG 20 33 or CG 20 38, grants status automatically to anyone a written construction agreement requires. Blanket is easier to administer at scale, since you do not chase a new endorsement per project, but it is conditional: no qualifying written agreement means no status. Scheduled forms are harder to collect and easier to prove.
Being the certificate holder means a certificate was addressed to you. It confers no coverage whatsoever. Additional insured means an endorsement extended the policy to you. The two appear in different boxes on an ACORD 25 and are routinely confused, including by the people preparing the certificates. This is worked through in full in the comparison of additional insured and certificate holder status.
The 11 85 edition of CG 20 10 covered completed operations and is still written into contract templates today, even though carriers no longer issue it. Every edition from 10 01 forward is ongoing operations only. The 04 13 edition added a cap tying your coverage to what your own contract required. The full history is in CG 20 10 edition dates.
An additional insured endorsement is a form attached to a liability policy that extends coverage under that policy to a party other than the policyholder. It is what actually creates the coverage. The certificate of insurance only reports that it was done. Without the endorsement, an additional insured requirement in your contract has not been satisfied, no matter what the certificate shows.
It is a separate page attached to the policy, headed THIS ENDORSEMENT CHANGES THE POLICY. PLEASE READ IT CAREFULLY, with the form number and edition date in the top right corner in the format CG 20 10 04 13. Scheduled forms carry a schedule box naming the additional insured. Blanket forms have no schedule, because status attaches automatically.
CG 20 10 grants additional insured status for the vendor ongoing operations, meaning while the work is being performed. CG 20 37 extends that status into the products-completed operations hazard, meaning after the work is finished. From the 10 01 edition onward you need both to be covered for the whole exposure, which is why contracts normally require the pair.
ISO publishes several dozen additional insured forms in the CG 20 series, each aimed at a different relationship: contractors, lessors of premises, vendors, mortgagees, ground lessors, permit-issuing agencies and others. In practice a business collecting certificates sees roughly a dozen of them, which are the ones listed in the table above.
Usually yes, and it is easier to administer than chasing a scheduled endorsement per project. The condition to check is that a written agreement requiring additional insured status exists and was signed before the work started, because that is what triggers the automatic grant. Also confirm completed operations is handled, since CG 20 33 and CG 20 38 do not include it.
Sometimes. Scheduled endorsements are often issued without an additional premium on smaller accounts, while blanket additional insured coverage is typically part of a broader endorsement package the vendor already carries. Where a charge applies it is usually modest relative to the policy premium. Cost is rarely the real obstacle. Producing the endorsement paperwork is.
No. The ACORD 25 states on its face that it is issued as a matter of information only, confers no rights upon the certificate holder, and does not amend, extend or alter the coverage afforded by the policies. Courts have consistently read that language as written. Only the endorsement grants the status.
It is a column on the ACORD 25 where the preparer indicates that additional insured status applies to a given policy line. It is a statement by whoever typed the certificate, not evidence from the carrier. Treat a ticked box as a prompt to request the endorsement, not as proof that one exists.
The named insured owns the policy, pays the premium, has the duty to cooperate and can make changes to it. An additional insured receives coverage under someone else policy, limited to the scope the endorsement grants, and has no control over that policy. An additional insured also generally cannot stop the policyholder from cancelling or amending it.
CG 20 11, Additional Insured, Managers or Lessors of Premises, is the form written for the landlord relationship. It covers liability arising out of ownership, maintenance or use of the part of the premises leased to the tenant. A construction-oriented form such as CG 20 10 is a poor fit for a straight lease, because it is keyed to operations the tenant performs for you.
They do different jobs and you generally want both. A waiver of subrogation stops the vendor insurer from coming after you to recover what it paid its own insured. An additional insured endorsement gives you coverage and a defense under the vendor policy when you are the one being sued. Neither substitutes for the other.
By extracting the form number and edition date from each endorsement as structured data and comparing it against the requirement recorded for that contract, rather than filing PDFs. That makes questions like which of my vendors lack completed operations coverage answerable in seconds, and it catches the edition changes carriers make quietly at renewal.
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