Certificate of Insurance (COI) in construction

A Certificate of Insurance proves to the party requesting it — usually the general contractor, the owner, or a lender — that a subcontractor or vendor has the insurance coverage the contract requires. The COI doesn't grant or extend coverage by itself; it's a summary of the policies that exist behind it.

In construction, the COI is the gating document for putting a sub on a project. Without a current COI showing the right coverage at the right limits with the right additional insureds, no sub should mobilize. A claim arising from work performed by an uninsured (or under-insured) sub typically falls back on the GC's policy — driving up premiums, deductibles, and the GC's Experience Modification Rate for years.

The Association for Cooperative Operations Research and Development (ACORD) publishes the standardized COI form used across the U.S. insurance industry. ACORD form 25 — formally titled "Certificate of Liability Insurance" — is the version used for commercial general liability, auto, umbrella, and workers' compensation. A single ACORD 25 can list all of those policies on one page.

The form is organized into rows for each policy: General Liability (GL), Automobile Liability, Umbrella/Excess Liability, Workers' Compensation, and Other. Each row shows the insurer's name, the policy number, the effective and expiration dates, and the limits. A separate "Description of Operations" box at the bottom lists additional insureds, waiver of subrogation, primary and non-contributory wording, and any project-specific endorsements.

Other ACORD forms exist for specialized coverages — ACORD 27 (Evidence of Property Insurance), ACORD 28 (Evidence of Commercial Property Insurance), ACORD 24 (older COI format) — but ACORD 25 is what 95%+ of construction COIs use.

Eight fields determine whether a COI is valid for your project:

• Insurer name and A.M. Best rating. Coverage from a non-admitted or low-rated carrier is a red flag. Most contracts require carriers rated A.M. Best A- VII or better.
• Policy numbers. Every coverage line must have a policy number. Blank policy numbers usually mean the coverage doesn't actually exist.
• Effective and expiration dates. The policy must be active during the period the sub works on the project. Expired or future-dated policies are invalid.
• Coverage limits. Per-occurrence and aggregate limits must meet your subcontract requirements. Common minimums: $1M/$2M GL, statutory WC + $500K–$1M employer's liability, $1M auto.
• Additional insureds. The GC (and often the owner) should be named as additional insureds on a primary and non-contributory basis for the GL policy. Check both the listed-name and the wording.
• Waiver of subrogation (WOS). Where required, confirm the WOS endorsement is in place for GL and WC.
• Project-specific endorsements. Larger projects often require project-specific aggregate endorsements (so the project doesn't share aggregate limits with other jobs).
• Certificate holder. The certificate holder block must show your company name correctly. A COI issued to a different party isn't valid for you.

1. "Per written contract" without the underlying endorsement. A COI that says additional insureds are added "per written contract" is only as good as the endorsement that's supposed to back it. Often the endorsement doesn't actually exist. Always require a copy of the additional insured endorsement (CG 20 10, CG 20 37, or similar) alongside the COI.

2. Generic "Additional Insured" wording without primary and non-contributory. An additional-insured endorsement that isn't primary and non-contributory can let the sub's insurer push the claim back to the GC's insurance, defeating the purpose of the endorsement.

3. Aggregate limits already eroded. A sub's $2M aggregate may already have $1.6M used by prior claims, leaving only $400K available for your project. The COI doesn't show erosion. For high-risk trades on bigger projects, require a per-project aggregate endorsement.

4. Expired policy from the same carrier. If a sub's COI shows a policy that expired last week, it doesn't matter that the rest of the form is filled in correctly. Coverage must be active during the work period.

5. Non-admitted surplus-lines carrier. Surplus-lines carriers are sometimes legitimate, sometimes problematic. They aren't backed by state guaranty funds. Verify A.M. Best rating before accepting.

6. Missing waiver of subrogation. Without WOS, the sub's insurer can sue your insurer to recover paid claims — creating a circular liability that increases everyone's premiums.

Most GCs start projects with the same plan: collect every sub's COI before mobilization, file it in a folder, set up a spreadsheet tracker with expiry dates, and renew before lapse. By month three of a busy job, the plan is broken. New subs start work before their COI is reviewed. Renewal dates slip past without anyone noticing. The COI tracker has three versions floating around between PMs and the office.

The structural problem: tracking 20–40 subs across 3–5 active projects, each with multiple policies and multiple expiry dates, is a full-time data-entry job. The expiry alert that should happen 30 days before lapse only happens if someone is looking at the spreadsheet that day. Most teams catch lapses retroactively — sometimes months late, when an audit or a claim forces the question.

Ella reads every Certificate of Insurance the moment it arrives in your project inbox — extracts the carrier, policy numbers, limits, dates, and additional insureds — and validates the COI against your subcontract requirements. She tracks expiry on every active COI and alerts your team at 30, 14, and 3 days before lapse. After expiration, any incoming invoice from that sub is held until a renewed COI is on file. Cross-project tracking handles subs working on multiple of your jobs — Ella validates additional insureds match every project the sub is invoicing.

See the full feature breakdown at the COI tracking page.