What Is a COI in Construction?
In construction, a COI (certificate of insurance) proves a subcontractor carries coverage. Here's what a construction COI shows, why GCs require it, and how to keep them current.
COI = Certificate of Insurance
On a jobsite, "COI" means certificate of insurance— the one-page proof that a subcontractor carries the coverage the general contractor requires. It's the document GCs collect from every trade partner before work starts. For the general version, see what a certificate of insurance is.
What a construction COI shows
- General liability limits — commonly $1,000,000 / $2,000,000.
- Workers' compensation — where the sub has employees.
- Additional insured status for the general contractor (see why that matters).
- Effective and expiration dates, and the carrier.
Why GCs require it
If a sub causes a loss and has no coverage, the claim can fall to the general contractor — raising premiums and eroding limits. Requiring a COI (and additional-insured status) pushes that risk back to the sub. More on this in do subcontractors need general liability insurance.
The hard part: keeping COIs current
A COI collected once is easy; keeping every sub's certificate valid — catching expirations and collecting renewals — is where GCs fall behind. A lapsed COI is the same as no COI when a claim hits. A contractor custom link issues compliant certificates automatically and tracks existing ones so nothing quietly expires.
Frequently asked questions
What is a COI in construction?
A COI (certificate of insurance) is a one-page document that proves a subcontractor or trade partner carries the required insurance — typically general liability and workers' compensation — and that the general contractor is named as additional insured.
Why do general contractors require a COI?
So the sub's own coverage responds first if the sub causes injury or damage, protecting the GC's policy and limits. An uninsured sub can push claims — and higher premiums — onto the general contractor.
What coverage does a construction COI usually show?
General liability (commonly $1M/$2M), workers' compensation where employees are involved, and additional-insured status for the general contractor. Larger projects may require auto and umbrella coverage too.