Additional Insured Endorsements, Explained

An additional insured endorsement gives a business partner, such as a landlord, general contractor or project owner, insured status on your general liability policy. What it covers depends on the form number: one family covers your ongoing operations and another covers your completed operations. No current edition raises your limits or covers a loss caused solely by the additional insured's own negligence.

The split that matters most is CG 20 10 versus CG 20 37. The first responds while your crews are still on the job; the second responds after the work is done, and construction contracts commonly require both. If you sign construction contracts or commercial leases, you have almost certainly been asked for one. Several of the programs behind our contractor general liability quotes offer blanket additional insured wording. Here is what the request actually means, based on the ISO forms most insurers use.

What is an additional insured?

An additional insured is a person or organization given insured status on your policy by endorsement because of a business relationship. The CGL already insures some people automatically: the named insured, and others such as employees acting within their duties (see what general liability insurance covers for the full list). An additional insured is a third category, added on purpose. Three relationships account for nearly every request. First, you do work for the party, such as a project owner or a general contractor hiring you as a subcontractor. Second, the party owns premises or equipment you use or lease, the landlord and equipment lessor case. Third, the party has a financial stake in your operation, such as a lender. The first two produce almost all requests, and construction produces almost all disputes.

Businesses demand the status because the contract promise alone can fail. Construction agreements and leases pair a hold harmless clause, your written promise to absorb the other party's losses, with an additional insured requirement, because that promise may not hold up on its own. Most states restrict indemnity by statute, and California Civil Code Section 2782 voids construction contract clauses that try to indemnify a party for its own sole negligence.^[1] When a court strikes the indemnity clause, the endorsement still stands. Insured status also brings practical advantages no contract clause can: the additional insured's defense is paid as a supplementary payment outside the limit, and your insurer will not subrogate against another insured on the same policy.

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

CG 20 10 covers the additional insured while your work is ongoing, and CG 20 37 covers it after the work is completed. The two most common endorsements split a construction project at completion:

CG 20 10 stops at completion, and construction claims routinely surface after completion. That is why contracts commonly require both endorsements, often with CG 20 37 kept in place for two or three years after completion, or for the statute of repose period. The same post-completion exposure is why builders risk and completed operations planning matter so much for contractors.

What about automatic additional insured status?

Automatic, or "blanket", additional insured endorsements grant insured status to anyone a written contract requires, without naming each party. ISO publishes them because scheduling every party on every project gets unwieldy. CG 20 33 covers ongoing operations for parties you contract with directly. CG 20 38 extends to other parties, such as a project owner, named in your customer's contract even if they never signed anything with you. CG 20 39 and CG 20 40 are the completed operations versions.

"Blanket" sounds like it covers everyone on the project, and most certificate reviewers treat it that way. It does not. These endorsements respond only when a written contract requiring additional insured status already exists, and that contract must be signed before the bodily injury or property damage happens. In practice, get the signature before the work that could cause a loss begins, not after the accident. Unsigned contracts, contracts signed mid-project and master agreements that lapsed before the work order are the classic blanket-form coverage fights.

The question of who agreed with whom has reached New York's highest court. In Gilbane Bldg. Co. v. St. Paul Fire & Marine Ins. Co. (2018), the construction manager on a state forensic laboratory project claimed additional insured status under the general contractor's policy because the owner's contract required it. The endorsement covered organizations "with whom you have agreed to add as an additional insured by written contract," and Gilbane had no such written agreement with the general contractor. Coverage failed on one preposition.^[2] That gap is exactly what CG 20 38 was built to close.

What does additional insured status not do?

Additional insured status does not cover sole negligence, raise limits, go beyond the contract or give the additional insured control of the defense. ISO tightened these forms in 2004 and later, and the limits matter to both sides:

• No sole-negligence coverage: the 2004 revision changed "arising out of" to "caused by," which requires a causal connection to the named insured's acts, omissions or work.
• No increase in limits: every insured, named and additional, shares the same limits, with no priority for anyone.
• No coverage beyond the contract: recent editions limit coverage to the lower of what the contract requires or the named insured's available limits.
• No control of the defense: the named insured's carrier investigates, defends and settles. The additional insured cannot make those decisions, and defending both parties can create real conflicts, since each one's best defense may be to blame the other.

If you are protected only as an additional insured, you are also subject to that policy's exclusions, its cancellation or nonrenewal, and its aggregate limits being used up by other claims without your knowledge. Additional insured status adds to your own CGL coverage but never replaces it.

What does "primary and noncontributory" mean?

"Primary and noncontributory" means the named insured's policy pays first and does not ask the additional insured's own insurer to share the loss. Contracts often add this as a second requirement. Without it, the CGL's Other Insurance condition can pull two primary policies into a sharing arrangement, and the additional insured's own policy ends up paying part of a claim it expected the named insured to absorb completely.

The fix is the Primary And Noncontributory: Other Insurance Condition endorsement (CG 20 01 12 19). It changes the Other Insurance condition so the named insured's policy responds first and does not seek contribution from the additional insured's insurance, when a written contract requires it.

When a request arrives, work through the contract's insurance exhibit in order. Identify which parties must be added and which form numbers or edition dates are named. Match each relationship to its form. Confirm that primary and noncontributory wording is actually attached, not assumed. Then show it with a certificate of insurance that lists the endorsements: a certificate alone confers no coverage, the endorsement does. When a contract asks for something outside standard practice, such as a discontinued edition like CG 20 10 11 85 or wording your carrier has not filed, talk to your broker before signing. Agreeing to insurance terms your policy cannot deliver is a breach of contract waiting for a claim to expose it.

This guide is for educational purposes and summarizes standard ISO policy language. Your policy's specific terms, conditions, and endorsements control. Talk to a licensed broker about your actual exposures.

Matching the endorsement to your contract

An additional insured endorsement gives a business partner insured status on your CGL policy, but only as far as that form number reaches. CG 20 10 covers your ongoing operations and CG 20 37 covers completed operations. Neither covers the other party's sole negligence or increases your limits. Get your endorsement schedule, read each endorsement, compare it with the contract's insurance exhibit, and make sure the contract is signed by both parties before work begins.