Certificates of Insurance (COI) for Subcontractors: What You Actually Need to Know

Subcontractor COIs explained: what a certificate of insurance is, what GCs actually look for, common mistakes, and how to keep your COI file compliant.

Coverage Explained | 8 min read | 2026-04-22

The COI is the single most-scrutinized document on a construction job. Here's what a general contractor actually checks for, what goes wrong, and how to keep your subcontractor COI file clean so work doesn't stop.

A certificate of insurance, or COI, is a one-page ACORD form that summarizes the policies you currently carry: general liability, workers' compensation, commercial auto, excess or umbrella, and sometimes professional liability or pollution. It lists the insurer, policy numbers, effective and expiration dates, and the limits of liability on each line. Most commercial insurance transactions —…

In This Article

• What a Certificate of Insurance Actually Is (and Isn't)
• What General Contractors Actually Look For
• The Six Most Common Subcontractor COI Mistakes
• Timing: How Fast You Can Actually Get a COI
• Maintaining a Subcontractor COI File as a GC
• What Subcontractors Should Keep on Hand

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