What is a Certificate of Insurance (COI)?
A Certificate of Insurance (COI) is the single most important document in contractor compliance. It proves your subcontractors carry valid insurance—and protects your company from liability.
Last updated August 2026
Definition
A Certificate of Insurance (COI) is a standardized document issued by an insurance broker or agency that serves as formal proof of insurance coverage. In commercial B2B relationships—particularly in construction, property management, and corporate operations—a hiring organization (the certificate holder) requires subcontractors and vendors to submit a COI before they are permitted to start work.
The most common standard COI form is the ACORD 25. This document summarizes key policy details on a single page: insurance company name, policy number, types of coverage, policy limits, and expiration dates. It also contains space to list additional insured entities, extending coverage protection to the hiring business.
Why COIs matter
Without a valid COI on file, your company is exposed to direct financial liability. If an uninsured subcontractor causes an accident or sustains an injury on your jobsite, your own general liability or workers' compensation coverage must absorb the loss. This is why tracking COI expiration dates and verifying coverage limits is critical.
Key Components of a COI
Commercial General Liability (CGL), Workers' Compensation, Commercial Auto Liability, and Excess/Umbrella Liability are the most common policy types listed.
The maximum payout per claim (per occurrence) and total policy lifetime (aggregate). Typical CGL limits are $1M per occurrence / $2M aggregate.
Each policy has an effective date and expiration date. Once expired, the coverage is void—and the contractor is non-compliant.
The hiring organization listed on the COI. This is the company requesting proof of coverage from the subcontractor.
An endorsement that extends the subcontractor's policy to cover the hiring company, protecting you from direct liability claims.
The insurance company providing the coverage. The carrier's A.M. Best rating indicates their financial reliability.
Common Coverage Requirements
| Coverage Type | Typical Limit | Purpose |
|---|---|---|
| Commercial General Liability | $1M / $2M | Covers property damage and bodily injury caused by the contractor |
| Workers' Compensation | Statutory limits | Covers employee injuries on the job—required by law in most states |
| Commercial Auto Liability | $1M combined | Covers vehicles used for business operations |
| Umbrella / Excess Liability | $1M–$5M | Additional coverage above underlying policy limits |
How SubDoc Automates COI Tracking
Send vendors a passwordless magic link to upload their COIs directly into your workspace.
SubDoc monitors every policy expiration date and calculates your real-time compliance score.
Automated email reminders are sent to vendors at 60, 30, and 7 days before expiry.
Every document upload, review, and status change is logged for audit-ready compliance records.
Start tracking COIs automatically
Stop chasing vendors for expired certificates. SubDoc automates collection, tracking, and alerts.