Blanket Additional Insured: What CG 20 33 and CG 20 38 Cover, and Who They Leave Out
A blanket additional insured endorsement covers whoever a sub has agreed in writing to cover, without naming anyone. Subs who work for many GCs prefer it, and it's fine when the contract behind it is right. This guide covers how the contract triggers it, the difference between CG 20 33 and CG 20 38, what neither covers, and why the certificate alone can't prove you're on it.
A blanket additional insured endorsement makes anyone the sub has agreed in a written contract to cover an additional insured on its general liability policy, with no name on the form. CG 20 33 covers only the party the sub contracted with, usually the GC. CG 20 38 also covers others that contract requires, such as the project owner. Both cover ongoing work only; CG 20 39 and CG 20 40 are the completed operations versions. Proof is the endorsement page plus your signed subcontract, not the certificate.
In this guide
What "blanket" means
A scheduled additional insured endorsement, such as CG 20 10, has a schedule with your name on it. A blanket endorsement has no schedule. ISO calls these forms "automatic status": anyone who meets the condition in the form becomes an additional insured without being named, and the condition is a written contract with the sub.
That is why subs and their brokers like them. A sub working for twenty GCs doesn't need twenty endorsements, and new contracts don't wait on the carrier. For you, it moves the proof somewhere else:
Scheduled (CG 20 10)
Your name on the endorsement is the proof. The endorsement page settles whether you're covered.
Blanket (CG 20 33, CG 20 38)
Nothing on the endorsement names you. Your signed contract with the sub is what brings you in, so the endorsement page plus the contract is the proof.
For how additional insured status differs from simply being the certificate holder, start there; this guide assumes you already require it.
The contract is the trigger
Both standard forms grant additional insured status to a party "for whom you are performing operations when you and such person or organization have agreed in writing in a contract or agreement" that it be added. Three things follow from that wording:
- It has to be in writing. A handshake, an email thread or a verbal "you're covered" doesn't meet the condition. An unsigned subcontract is the most common way a blanket endorsement ends up covering nobody.
- The sub has to be working for you. The grant is tied to operations performed for the additional insured, and to liability caused in whole or in part by the sub's acts or omissions in that work.
- The contract sets the ceiling. The cover is never broader than the contract requires, and the limit is the lesser of the contract amount and the policy limits. A $1 million requirement gets $1 million, whatever the sub carries.
So the subcontract's insurance exhibit does more work with a blanket form than with a scheduled one. It should name every party to be added, require both ongoing and completed operations, and be signed before the sub mobilises. Subcontractor insurance requirements covers what that exhibit usually asks for.
CG 20 33 vs CG 20 38
The two forms read the same, line for line, except for one clause. CG 20 38 adds a second group of additional insureds: "any other person or organization you are required to add" under the same contract.
| CG 20 33 | CG 20 38 | |
|---|---|---|
| Who's covered | The party the sub agreed in writing to add, that it's working for | That party, plus anyone else the same contract requires the sub to add |
| Project owner when the sub's contract is with the GC | Not covered: the owner has no contract with the sub | Covered, if the subcontract requires the owner to be added |
| When status ends | When the sub's operations for you are completed | When the sub's operations for you are completed |
| Completed operations counterpart | CG 20 39 | CG 20 40 |
| Fits | A direct hire with no one above you to protect | A subcontract under a prime contract, which is most construction work |
A worked example. An owner hires you as GC, and the prime contract requires every sub to add the owner and you as additional insureds. You subcontract the electrical work, and the subcontract repeats that requirement. A worker is hurt and sues everyone, owner included.
| Party | Electrical sub carries CG 20 33 | Electrical sub carries CG 20 38 |
|---|---|---|
| You, the GC | Additional insured: you contracted with the sub | Additional insured |
| The owner | Not an additional insured: no contract with the sub. You may now owe the owner under the prime contract | Additional insured: the subcontract requires it |
The CG 20 33 gap lands on the GC: the prime contract promised the owner would be covered by every sub, and it wasn't. If your prime contract has that requirement, specify CG 20 38 and CG 20 40, or scheduled forms naming the owner.
The blanket forms and their scheduled equivalents
ISO's construction additional insured forms come in pairs, one for the work in progress and one for after it's finished. A blanket requirement needs both halves, just as a scheduled one does:
| Who's covered | During the work | After the work |
|---|---|---|
| Named in a schedule | CG 20 10 | CG 20 37 |
| Blanket: the party the sub contracted with | CG 20 33 | CG 20 39 |
| Blanket: that party and others the contract requires | CG 20 38 | CG 20 40 |
CG 20 39 and CG 20 40 use the same contract triggers for injury or damage caused by the sub's finished work. The CG 20 10 vs CG 20 37 guide explains why the after-the-work half matters: on construction, that's when many claims arrive. Owners, landlords and property managers outside construction often see a different form, CG 20 26, which names them with no project attached.
What else they leave out
Finished work
CG 20 33 and CG 20 38 end additional insured status when the sub's operations for you are completed, and exclude injury or damage once all work on the project is done or the work has been put to its intended use. Require CG 20 39 or CG 20 40 as well.
Design and inspection work
Both forms exclude claims from professional architectural, engineering or surveying services, including drawings, change orders and supervisory or inspection activities. A design-build sub needs professional liability for that.
Anything beyond the contract
The cover is no broader than the contract requires, and the limit is the lesser of the contract amount and the policy limits.
Carrier wording
Many carriers use their own blanket forms instead of ISO's, and some combine several grants in one endorsement. The trigger can differ, for example a contract signed before the loss, or before the work. Read the form you're given rather than assuming it matches CG 20 38.
Additional insured status also doesn't decide whose policy pays first. That is primary and noncontributory wording, a separate requirement.
How to require it and check it
On the ACORD 25, the general liability row's ADDL INSD box and a line in Description of Operations, such as "additional insured status applies where required by written contract", are the agent's statements. The certificate says itself that it doesn't amend the policy. With a blanket form, there is no name to check on the certificate either.
Name every party in the subcontract
List yourself, the owner and anyone else your prime contract names, and require additional insured status for ongoing and completed operations.
Get the subcontract signed before work starts
The blanket form only reaches parties the sub agreed in writing to add. A crew on site under an unsigned subcontract may have no cover in your favor.
Ask for the endorsement pages
Check the form numbers: CG 20 38 with CG 20 40 if anyone above you must be covered, or the carrier's equivalents. A CG 20 33 alone won't reach the owner.
Read carrier forms, not just numbers
If the form isn't ISO's, read the grant, the trigger and the end of cover before you accept it.
Check again at renewal
Endorsements can drop off when a policy renews or the sub changes carriers.
Two endorsements per sub, each on its own renewal date, is the check that slips first. Insurance endorsement verification reads the forms themselves, and COI tracking software keeps each policy on its own dates so the renewal check happens. The COI audit checklist covers the rest of the certificate.
How TrackMyVendor automates this
- The ADDL INSD box is read on every coverage row of the certificate, along with the carrier, policy number, dates and limits.
- Endorsement forms are read, recognised as additional insured cover by form number, and recorded as blanket or scheduled, with the names when a schedule has them. Pro
- Require the additional insured endorsement on your checklist, and a sub who hasn't sent one shows it as missing until it arrives. Starter
We read the certificates and endorsement forms you're sent; we don't read the subcontract, so we can't confirm a blanket form's written-contract condition is met. That stays with you and your attorney.
See how endorsement verification worksCertificates and endorsements, collected together
Subs upload the certificate and the endorsement pages through one link — no account, no portal. Every policy is read and tracked on its own dates. Your first 25 contractors are free.
Frequently asked questions
What is a blanket additional insured endorsement?
What is the difference between CG 20 33 and CG 20 38?
Does a blanket additional insured endorsement cover completed operations?
Is a certificate of insurance enough to prove blanket additional insured status?
Is a blanket endorsement as good as CG 20 10?
This guide explains how the standard ISO blanket additional insured forms commonly work. It isn't insurance or legal advice: editions, carrier wording and state law differ, and the policy and your contract govern. Ask your broker and attorney about your own requirements.
Insurance on a sub’s certificate
What to require from every sub, one term at a time.
Subcontractor insurance requirements: start here → Coverage, minimums and endorsements to require from subs, with every term below in one table