What Does "Additional Insured" Mean? A Plain-English Guide for California Businesses

An additional insured is a person or company that is not the policyholder but has been added to someone else's liability policy by endorsement. That gives them their own right to defense and payment under that policy, within limits. In practice, it's how a property owner, general contractor, landlord or client gets protection under the general liability insurance of the business doing work for them.

The key word is endorsement. Being listed on a certificate of insurance doesn't make anyone an additional insured. The policy itself has to be changed. Many contract disputes in California start with someone who thought they were covered and wasn't.

Below: what additional insured status gives you, the ISO endorsements named in contracts, and how California's anti-indemnity statutes limit them. It's the first thing to understand in any contractors insurance program.

Named insured vs additional insured vs certificate holder

Role	How they get there	What they get
Named insured	Listed on the policy declarations	Full coverage under the policy, subject to its terms. Pays the premium, receives notices, owns the policy.
Additional insured	Added by an endorsement to the named insured's policy	Coverage as an insured, but only for the situations the endorsement describes, usually liability tied to the named insured's work or operations.
Certificate holder	Named in the "Certificate Holder" box of an ACORD 25	A copy of the certificate. No rights under the policy.

Most contracts require you to be both. Certificate holder status alone gives you nothing beyond a piece of paper.

Why a certificate alone doesn't make you an additional insured

The current certificate form, the ACORD 25 (2025/12), says this in its top box: the certificate "is issued as a matter of information only and confers no rights upon the certificate holder," and it "does not affirmatively or negatively amend, extend or alter the coverage afforded by the policies below."

The next box is even more direct. If the certificate holder is an additional insured, "the policy(ies) must have ADDITIONAL INSURED provisions or be endorsed," and "a statement on this certificate does not confer rights to the certificate holder in lieu of such endorsement(s)."

California law backs this up. Insurance Code §384 requires a certificate of insurance used in place of the policy to state, in substance, that it "is not an insurance policy and does not amend, extend or alter the coverage afforded by the policies listed herein," and that the coverage is subject to all the policy's terms, exclusions and conditions.

A "Y" in the ADDL INSD column is the agent reporting an endorsement. If none was issued, the certificate can't create one. Ask for a copy of the endorsement. Our certificate of insurance request template includes that request in the wording, and our guide on how to read a certificate of insurance shows where additional insured status appears on the form.

What an additional insured actually gets

When the endorsement is in place, the additional insured typically gets:

• A defense. If they're sued over something covered by the endorsement, the named insured's carrier generally has a duty to defend them.

• Payment of covered damages, up to the applicable limit and subject to the policy's exclusions.

• A direct claim. The additional insured can tender a claim straight to the named insured's carrier.

What an additional insured does not get

Under most standard ISO endorsements:

• No coverage for their own sole negligence. Since the 2004 editions, the standard ISO owners/lessees/contractors endorsements cover liability "caused, in whole or in part, by" the named insured's acts or omissions. If the injury was entirely the additional insured's fault, the endorsement typically doesn't respond.

• Only the work described. Coverage is tied to the named insured's operations for that additional insured, often at a scheduled location or project.

• Limits no greater than the contract requires. The 2013 editions limit coverage to the lesser of the limits the contract requires or the policy limits, and coverage "will not be broader than" what the contract requires.

• Only "to the extent permitted by law." Since 2013, the standard endorsements also include language that limits coverage to what state law allows. In California, that brings the anti-indemnity statutes covered below into play.

• Shared limits. The additional insured shares the named insured's limits. If the aggregate has been used up by other claims, there may be little left. This is why contracts often ask for a per-project aggregate, and why umbrella or excess liability limits matter on larger jobs.

• Not necessarily primary. Without a separate endorsement, the additional insured's own insurance may have to share the loss. That's what primary and non-contributory wording addresses.

Many carriers use their own forms instead of ISO's, so read the actual endorsement.

The ISO endorsements you'll see in contracts

Most construction and vendor contracts in California name ISO (Insurance Services Office) forms by number, or ask for "CG 20 10 and CG 20 37 or equivalent."

CG 20 10: ongoing operations

CG 20 10, Additional Insured – Owners, Lessees or Contractors – Scheduled Person or Organization, covers the additional insured for liability arising out of the named insured's ongoing operations, meaning while the work is being performed. It's "scheduled" because the additional insured (and often the project or location) is named in the endorsement's schedule.

Since the 2001 editions, CG 20 10 does not cover completed operations. Once the work is finished, CG 20 10 alone no longer protects the additional insured.

CG 20 37: completed operations

CG 20 37, Additional Insured – Owners, Lessees or Contractors – Completed Operations, was introduced to fill that gap. It covers the additional insured for injury or damage arising out of "your work" after it's been completed. That's the period when most construction defect and post-job injury claims show up.

A contract that asks for "ongoing and completed operations" coverage needs both: CG 20 10 and CG 20 37, or the carrier's equivalents.

Edition dates

ISO revises these forms periodically, and the edition date (shown as month and year, e.g., "04 13") matters.

Edition	What changed
10 01	CG 20 10 limited to ongoing operations; CG 20 37 introduced for completed operations
07 04	"Arising out of" replaced with "caused, in whole or in part, by" the named insured's acts or omissions
04 13	Added "to the extent permitted by law," coverage no broader than the contract requires, and limits capped at the contract amount
12 19	Revised the limits wording ("shall not increase the applicable limits of insurance"); introduced new blanket completed-operations forms

If your contract names a specific edition, check with your agent before you sign. Your carrier may not offer it.

Scheduled vs blanket endorsements

A scheduled endorsement names each additional insured individually, which suits a one-off project. A blanket (or "automatic") endorsement adds anyone the named insured has agreed in a written contract to add, without naming them. The common ISO blanket forms:

Form	What it does
CG 20 33	Automatic additional insured status for ongoing operations when you've agreed in a written construction contract with that party. Has been read in some cases to require a direct contract.
CG 20 38	Like CG 20 33, but also extends status to other parties you're required to add under that contract (for example, the project owner named in your subcontract with the GC), even without a direct contract with them.
CG 20 39 (12 19)	Automatic status for completed operations where you and the additional insured have agreed in writing.
CG 20 40 (12 19)	Automatic completed-operations status for parties you're required to add under a written contract, without direct privity.

Blanket endorsements usually require the written contract to be signed before the injury or damage occurs.

Not sure your additional insured endorsement matches what your contracts require? TSM is an independent agency — we compare carriers for you. Call (209) 524-6366 (Modesto) or (530) 221-3031 (Redding).

California anti-indemnity law and additional insured requirements

California limits how far a construction contract can shift liability. Those limits apply both to indemnity clauses and, in many cases, to requirements to insure the other party.

Civil Code §2782: sole negligence, public agencies and owners

Civil Code §2782(a) makes void and unenforceable any clause in a construction contract that tries to indemnify the promisee (the party being protected) against liability arising from its sole negligence or willful misconduct, or from design defects it furnished.

Other subdivisions go further for specific relationships:

• Public agencies (§2782(b)): clauses that shift a public agency's active negligence onto a contractor are void.

• Private owners (§2782(c)): for contracts entered into on or after January 1, 2013, clauses that shift liability from an owner of privately owned property are unenforceable to the extent of the owner's active negligence. This doesn't apply to a homeowner improving their own single-family home.

• Residential construction (§2782(d)): for residential construction contracts entered into after January 1, 2009, provisions requiring a subcontractor to insure or indemnify a builder or general contractor against construction defect claims are unenforceable to the extent the claims arise from the builder's or contractor's negligence, or fall outside the subcontractor's scope of work.

Civil Code §2782.05: subcontracts on commercial work

Civil Code §2782.05(a) applies to construction contracts entered into on or after January 1, 2013, subject to the exceptions in subdivision (b). It makes void and unenforceable any provision that purports to "insure or indemnify, including the cost to defend," a general contractor, construction manager or other subcontractor, by a subcontractor, to the extent the claims arise from that party's active negligence or willful misconduct, from design defects it furnished, or from matters outside the subcontractor's scope of work. The section can't be waived by agreement.

Notice the word insure. A subcontract can't use an additional insured requirement to get around what it couldn't do through an indemnity clause.

Subdivision (b) lists exceptions. Among them:

• Residential construction covered by Title 7 (Civil Code §895 and following), which §2782(d) addresses instead.

• Wrap-up insurance policies or programs (OCIPs and CCIPs).

• A provision requiring the subcontractor to buy insurance covering the subcontractor's own acts or omissions, expressly including additional insured endorsements for ongoing and completed operations.

That last exception explains how CG 20 10 and CG 20 37 still work in California. A GC can require a sub to name it as an additional insured for liability caused by the sub's work. What the GC can't do is use that requirement to make the sub's policy pay for the GC's own active negligence.

Practical takeaway: if your subcontract demands that your insurance cover the GC "regardless of fault," or for claims unrelated to your work, that clause may be unenforceable. Have the insurance section reviewed before you sign, and talk to an attorney about the indemnity language.

How to get it right, from either side

If you're the one being added: put the requirement in the written contract before work starts, naming the exact entity. Ask for the certificate and a copy of the endorsement, confirm both ongoing and completed operations are covered, and check for primary and non-contributory wording and a waiver of subrogation if your contract requires them. Our guide to verifying a contractor's insurance has a simple tracking process. Landlords get the same protection from tenants through a "managers or lessors of premises" endorsement. See landlord liability insurance.

If you're the one adding them: send the contract's insurance section to your agent before you sign. Ask whether you already have a blanket endorsement, and watch for contracts that name editions your carrier doesn't offer, or that demand coverage California law won't enforce. Remember that the additional insured shares your limits, so a year with several claims can wear down the aggregate for everyone. If you're a California contractor, it also helps to know how these requirements differ from your licensing obligations. See CSLB license bond vs liability insurance.

FAQs

What does it mean to be listed as an additional insured?

It means the named insured's liability policy has been endorsed to cover you as an insured, usually for liability arising out of the named insured's work or operations for you. You can tender claims directly to their carrier and typically receive a defense, within the endorsement's limits and the policy's exclusions.

Is a certificate holder the same as an additional insured?

No. A certificate holder receives a copy of the certificate of insurance and has no rights under the policy. An additional insured has been added to the policy by endorsement. The ACORD 25 itself says a statement on the certificate does not confer rights in place of an endorsement.

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

CG 20 10 covers the additional insured during the named insured's ongoing operations. CG 20 37 covers them after the work is completed. Contracts that require "ongoing and completed operations" coverage need both, or equivalent carrier forms.

Does an additional insured endorsement cost extra?

Sometimes. Many carriers include a blanket additional insured endorsement in contractor packages. Others charge per scheduled endorsement or for broader forms. The certificate itself is normally free; the endorsement may not be.

Does additional insured coverage protect someone from their own negligence?

Generally not for their sole negligence under the current ISO forms, which require the injury to be caused at least in part by the named insured. In California construction contracts, Civil Code §§2782 and 2782.05 also limit attempts to shift a general contractor's or owner's active negligence onto a subcontractor's insurance.