Additional insured status gives someone else rights under your general liability policy, generally limited to liability arising out of your work for them. Contracts usually ask for it on both ongoing operations (while you work) and completed operations (after the job is done), often on a primary and non-contributory basis, together with a waiver of subrogation. A certificate of insurance with the AI box checked is evidence, not coverage; the endorsement is what counts.
What additional insured status actually does
When a client or general contractor is an additional insured on your policy and someone sues them over your work, your insurer is generally obligated to defend them and pay covered damages, within your limits. That is why every owner and upstream contractor wants it: it moves the first dollar of a claim about your work onto your policy instead of theirs.
- It is limited in scope. Modern endorsements generally cover the additional insured only for injury or damage caused, in whole or in part, by your acts or omissions in the work you do for them.
- It shares your limits. A claim paid for an additional insured uses up the same limits that protect you.
- Your exclusions still apply. If your policy excludes a type of work or claim, the additional insured does not get around that exclusion.
- Newer editions are tied to the contract. Many current forms give coverage only to the extent the written contract requires and the law permits.
Ongoing vs completed operations (CG 20 10 and CG 20 37)
Construction claims come in two waves, and additional insured coverage is split the same way.
- Ongoing operations (CG 20 10)Covers the additional insured for claims arising while your work is in progress, such as a worker or visitor injured on site or damage to neighboring property during the job.
- Completed operations (CG 20 37)Covers the additional insured for claims arising after your work is finished, such as a construction defect that causes water damage or an injury years later.
These are the standard ISO form numbers, and many contracts name them specifically, sometimes with an edition date. Insurers also use their own forms that may or may not match. If your contract calls for both and your policy only carries ongoing operations, the owner may be uncovered for exactly the kind of claim construction contracts worry about most. Contracts also often require completed operations coverage to stay in place for several years after the job.
Blanket vs scheduled additional insured
There are two ways to add someone to your policy, and the choice affects how fast you can start a job.
- ScheduledThe additional insured is named on the endorsement by name. Each new client means a request to the insurer, and the policy is only as good as the list.
- BlanketThe endorsement automatically includes anyone you have agreed in a written contract to add. No per-job change is needed, which is why most active contractors want it.
Blanket endorsements come with conditions worth knowing. Most require a written contract, many require it to be signed before the work or the loss, and some apply only to owners and contractors you work for directly, not to parties further up the chain. A handshake job does not trigger a blanket endorsement that requires a written contract.
Primary and non-contributory
When two policies could respond to the same claim, they normally share it. A primary and non-contributory provision changes that: your policy responds first on behalf of the additional insured, and your insurer agrees not to seek contribution from the additional insured’s own policy.
Owners and general contractors ask for this so that a claim about your work never touches their own loss history. It is a separate endorsement or policy provision, not something additional insured status provides automatically, so if the contract asks for it, the policy needs to say it.
Waiver of subrogation
After paying a claim, an insurer normally has the right to recover from whoever caused the loss. That is subrogation. A waiver of subrogation is your insurer agreeing, in advance, not to pursue the party you name.
- On general liability, it stops your insurer from suing the owner or general contractor to recover a claim it paid.
- On workers’ comp, it stops your comp insurer from suing them after paying for your injured employee. This is one of the most common requirements in construction contracts.
- On commercial auto and umbrella, contracts often ask for it too.
Like primary and non-contributory, it is a separate endorsement. Some are blanket, some must be scheduled per job, and some insurers add a charge for them.
Why the certificate box isn’t the endorsement
A certificate of insurance is a summary. The standard certificate form says on its face that it confers no rights on the holder and does not amend or extend the policy. Checking the “additional insured” box on a certificate does not make anyone an additional insured; only the endorsement on the policy does.
That is why careful owners and general contractors ask for copies of the endorsements themselves, not just the certificate. If the certificate says something the policy does not, the certificate generally loses. Before you sign a contract, put its insurance section through the contract requirements reader; before you accept a sub’s paperwork, run it through the certificate checker.
What to check before you sign a contract
- Who must be added: owner, general contractor, lender, property manager, exactly as named.
- Ongoing, completed, or both, and for how many years after completion.
- Form numbers or edition dates the contract names, and whether your forms match.
- Primary and non-contributory wording.
- Waivers of subrogation on which policies.
- Umbrella requirements, since many contracts want the additional insured to follow up into the excess layer.
Send me the insurance section of the contract before you sign it, and I will tell you what your current policy already does and what it does not. How I put contractor programs together.
Common questions
What does it mean to be an additional insured?
It means you have been added to someone else’s liability policy by endorsement, so their insurer will generally defend and cover you for claims arising out of their work for you, within their limits and subject to their policy’s terms.
What is the difference between CG 20 10 and CG 20 37?
They are the standard ISO additional insured endorsements for contractors. CG 20 10 covers ongoing operations while the work is in progress; CG 20 37 covers completed operations after the work is finished. Many contracts require both.
Is a certificate of insurance enough to prove additional insured status?
No. A certificate states that it confers no rights and does not change the policy. Additional insured status exists only if the endorsement is on the policy, which is why many owners ask for a copy of the endorsement.
What does primary and non-contributory mean?
It means your policy pays first for the additional insured and does not seek contribution from their own insurance. It is a separate provision that must be on your policy if the contract asks for it.
Does adding an additional insured reduce my coverage?
It can. Claims paid on behalf of an additional insured use the same limits that protect you, which is one reason contracts that require several additional insureds often require an umbrella as well.
General information about additional insured endorsements as of October 2026, not legal advice. Endorsement wording differs by insurer and edition; contract indemnity and insurance questions belong with your attorney. Coverage depends on underwriting and the terms, conditions and exclusions of the policy actually issued.