When a general contractor requires a subcontractor to add them as additional insured, two other endorsements almost always come along for the ride: primary & non-contributory and waiver of subrogation. Together with additional-insured status, they're the "big four" you're really checking on a sub's general liability. Here's what each one does — in plain English.
Primary & non-contributory (PNC)
Normally, when two policies could cover the same claim, the insurers "share" the cost. Primary & non-contributory overrides that: it says the subcontractor's policy must pay first and in full ("primary"), and must not ask your policy to chip in ("non-contributory").
Why GCs require it: without PNC, even if you're an additional insured on the sub's policy, their insurer could force your insurer to share a claim that was the sub's fault — driving up your premiums and eating your loss history. PNC keeps the sub's coverage truly first in line.
Waiver of subrogation
"Subrogation" is an insurer's right to recover what it paid out by going after whoever caused the loss. A waiver of subrogation is the subcontractor's insurer agreeing, in advance, not to come after you to recover those costs.
Why GCs require it: without the waiver, the sub's insurer could pay a claim and then turn around and sue you to get the money back — which defeats the point of being protected. The waiver closes that loop. It's commonly required on both general liability and workers' compensation.
The big four, together: additional insured (ongoing and completed operations), primary & non-contributory, and waiver of subrogation. Most construction contracts require all of them — and, like additional-insured status, each is added by an endorsement. The certificate's checkbox or "Description of Operations" text is a claim, not proof; confirm the actual endorsement forms.
How to verify them
- On the ACORD 25, the SUBR WVD column flags a waiver of subrogation, and PNC is usually noted in the Description of Operations — but treat both as claims to confirm, not proof.
- Request the actual endorsement forms from the sub's agent and confirm the wording and that your entity is covered.
- Re-check at every renewal — endorsements can change when a policy renews.
Want the full list? Grab the free Subcontractor COI Verification Checklist, or run a certificate through the free COI Checker to see what's missing.
Verify all four — automatically
CoverProof reads each certificate and checks additional insured, primary & non-contributory, waiver of subrogation, limits, and expiry against your requirements — flagging what's only claimed vs. actually evidenced — and chases renewals for you.
or try the free COI Checker →This article is general information, not insurance or legal advice. Requirements vary by contract and jurisdiction; confirm specifics with your broker or counsel.