Certificate of insurance (COI)

Definition

Proof of the coverage a commercial client demands before it will hire a contractor at all.

Why It Matters

Most commercial accounts will not sign without one, so the coverage is both an operating cost and the gate to the better half of the revenue. Ask what limits the current clients require, because a single large account can set the bar for the whole company, and confirm what that coverage costs at your own claims history rather than the seller's. Being unable to produce one is being unable to bid.