Additional insured endorsements: CG 20 10 vs CG 20 37
Being an 'additional insured' on a vendor's general liability policy means their insurance defends and covers you for liability arising from their work. It's the single most demanded protection in commercial contracts — and the most commonly faked-by-checkbox on certificates.
Two ISO endorsement forms do most of the work, and the difference between them decides whether you're covered after the job is done.
CG 20 10 — ongoing operations
The CG 20 10 ('Additional Insured — Owners, Lessees or Contractors — Scheduled Person or Organization') covers you for liability arising from the vendor's ONGOING operations — while the work is happening. The moment the work is completed, CG 20 10 coverage generally stops. Editions matter: the 1985 edition was broader; post-2004 editions narrow coverage to liability caused at least in part by the insured's acts.
CG 20 37 — completed operations
Most construction defect and injury claims surface AFTER completion — the deck fails a year later, the wiring shorts after handover. That's completed operations liability, and it needs the CG 20 37 ('Additional Insured — Completed Operations'). Construction contracts typically require both forms: 20 10 for the build, 20 37 for the years after.
Verifying additional insured status properly
The verification checklist:
- The endorsement forms (or carrier equivalents) are physically attached behind the certificate — the ADDL INSD checkbox proves nothing.
- Scheduled endorsements name your exact legal entity; blanket endorsements require a written contract in place — make sure yours qualifies.
- Both ongoing (CG 20 10) and completed operations (CG 20 37) forms are present when your contract requires completed-ops coverage.
- Form editions and policy numbers match the certificate face.
Frequently asked questions
What is a blanket additional insured endorsement?
An endorsement that grants AI status automatically to any party the named insured agreed in a written contract to add — no schedule needed. It's convenient, but your protection then depends on having a signed contract with AI language before the loss.
Does additional insured status cover my own negligence?
Generally no under modern forms — post-2004 ISO editions limit coverage to liability caused in whole or part by the named insured's work. Your own sole negligence stays on your own policy.
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