Additional Insured Endorsement
A policy endorsement adding another party, typically the owner or general contractor, as an additional insured on a subcontractor's liability policy, extending that policy's coverage to protect the additional insured for liability arising from the subcontractor's work.
Why it matters
A [[concept-certificate-of-insurance|certificate of insurance]] showing additional insured status isn't proof the endorsement was actually issued, the certificate is just a snapshot someone filled out, the endorsement itself is the actual policy language that has to be verified separately.
On a real project
A general contractor's contract requires every subcontractor to name it as an additional insured, and the risk manager verifies the actual policy endorsement, not just the certificate of insurance, before allowing that subcontractor to mobilize on site.
Who this matters most to
A Risk Manager verifies additional insured endorsements are actually issued, not just claimed on a certificate, while a Contracts Administrator tracks which subcontracts require it.
Where this goes wrong
A GC's contract requires every subcontractor to name it as an additional insured, but the contracts administrator never actually verifies the endorsement was issued, just files the certificate of insurance without checking further. A claim arises, and the GC discovers it was never actually added as an additional insured, leaving it without the coverage the contract was supposed to guarantee.