"Additional insured" sounds like a yes-or-no thing: either you're on the other party's policy or you're not. It isn't. Being named additional insured covers you for one of two very different time windows — while the work is happening, or after it's finished — and a lot of endorsements only give you the first. For most businesses that's a footnote. For anyone in construction, it's the whole ballgame, because the claims that hurt most show up *after* everyone's gone home. Here's the trap and how to close it.
Two windows, not one
When you require additional-insured status from a contractor, sub, or vendor, the coverage comes in two flavors:
- Ongoing operations — you're covered under their policy while they're actively performing the work. A sub drops a tool on someone during the job, and you (named additional insured) have coverage under the sub's policy for the claim.
- Completed operations — you're covered after the work is finished, for claims arising out of the completed project. The sub's completed work fails two years later and causes damage, and your additional-insured status still responds.
The problem: plenty of endorsements grant ongoing operations only. The moment the work is complete, that coverage ends — and so does your protection under their policy.
Why this is a construction problem specifically
Construction-defect and completed-work claims are notorious for showing up late. A roof that leaks after three winters. A foundation that settles. A weld that fails. A system that was fine at closeout and isn't anymore. These claims routinely surface years after the project closed — which is exactly when ongoing-operations-only additional-insured status has already expired.
So the general contractor who collected certificates from every sub, felt protected, and then gets hit with a defect suit four years later discovers the additional-insured coverage they were counting on covered only the active build. The sub is long gone, and the GC's own general liability is left to answer for the sub's completed work. That's the trap.
The form numbers (and why they matter)
On the standard ISO endorsements, the distinction usually breaks down like this:
- CG 20 10 — generally covers ongoing operations.
- CG 20 37 — adds completed operations.
That's why well-drafted construction contracts require both — often written as "CG 20 10 and CG 20 37" — so the additional-insured protection covers the full life of the risk, during and after. Blanket endorsements can cover both for anyone you're contractually required to add, which is convenient, but the wording and edition date still matter.
The practical takeaway isn't to memorize form numbers — it's to require completed operations explicitly and then confirm the actual endorsement is on the policy, because a certificate of insurance that merely says "additional insured" tells you nothing about which window you got.
How to close the gap
- Require both windows in writing. Your contract should ask for additional-insured status for ongoing and completed operations, not just "additional insured."
- Pair it with primary and non-contributory wording, so their policy pays first in both windows.
- Verify the endorsement, not the certificate. For any sub whose work could fail later, get the actual endorsement form — this is a core part of what to collect from subcontractors before work starts.
- Mind the tail. Completed-operations coverage only helps if the sub keeps their policy (and that coverage) in force after the job. A sub who drops coverage takes your protection with them.
Our approach
At Cory Washington & Co., we make sure the additional-insured status you *require* — and the status you *grant* — matches the real life of the risk, not just the active job. For contractors, that means building completed-operations into both sides of your program: what you demand from your subs and what you promise your clients. The point is that when a defect claim surfaces years later, the coverage you were counting on is actually still there.
Collecting certificates but unsure they cover completed operations? Request a coverage review and we'll check the endorsements, not just the paperwork. For the full picture of how these requirements get written into a deal, see the insurance section of a contract, decoded.
Frequently Asked
What is the difference between ongoing and completed operations additional insured?
Ongoing operations additional-insured coverage protects you while the other party's work is actively in progress. Completed operations coverage protects you after the work is finished — for claims that arise from the completed project, like a defect that fails later. Many additional-insured endorsements grant ongoing operations only. Since construction-defect claims often surface years after a job closes, you need completed-operations coverage too, or you're exposed exactly when those claims appear.
Which additional-insured endorsement covers completed operations?
On the common ISO forms, CG 20 10 generally covers ongoing operations, while CG 20 37 adds completed operations — which is why contracts often require both. Blanket endorsements may cover both where you're contractually required to be added. The form number and its edition date matter, so the safest practice is to require completed-operations additional-insured status explicitly and confirm the actual endorsement, not just a certificate that says 'additional insured.'
Why do completed operations matter so much in construction?
Because construction-defect and completed-work claims frequently appear long after the project is done — a failure, a leak, a collapse traced to work finished years earlier. If your additional-insured status on a subcontractor's policy only covered ongoing operations, it expired when they packed up, leaving you with no coverage under their policy for exactly the kind of claim that shows up late. Completed-operations coverage keeps the protection alive for that tail.
This article is general information for business owners, not insurance or legal advice, and does not bind or alter coverage. Policy terms, eligibility, and pricing vary by carrier and state — confirm specifics with our licensed team before making decisions.