Most GCs know to ask for a certificate of insurance (COI) before a sub sets foot on site. Fewer actually read past the top line. A COI is a single-page summary, but the details that protect you — additional insured status, per-occurrence versus aggregate limits, and whether coverage is actually current — are easy to skim past under deadline pressure. Here's what each section is actually telling you.
Confirm it came from the insurer, not the subcontractor
A legitimate COI is issued directly by the insurance company or broker, addressed to you (or your project) as the certificate holder. Request it sent directly from the insurer's email or portal rather than accepting a forwarded PDF or photo from the sub — this closes the most common way COIs get misrepresented or altered.
General liability: read both limits, not just one
General liability coverage lists two limits: 'each occurrence' (the maximum paid for a single incident) and 'general aggregate' (the total cap across all claims in the policy period). A sub can look well-covered on the occurrence limit while running close to their aggregate cap from other claims — ask when the aggregate resets and confirm it hasn't already been substantially drawn down by other jobs.
Workers' compensation: no crew, no exception
If a subcontractor has any employees on site, workers' comp coverage is not optional — without it, an on-site injury becomes a liability claim against you and your project, not just the sub. A one-person operation using only 1099 subcontractors of their own may show a workers' comp exemption; if so, confirm that exemption is actually filed with the state, not just claimed.
'Additional insured' status: this is the line most GCs miss
Being listed as the certificate holder is not the same as being named an additional insured. Certificate holder status means you receive a copy of the certificate; additional insured status means the sub's policy actually extends coverage to you for claims arising from their work. If your contract requires additional insured status, confirm it's reflected with an actual endorsement, not just your name in the certificate holder box — a COI can list you as holder while your name never appears on the additional insured endorsement.
Check the dates, every time
Confirm the policy's effective and expiration dates cover your project's full expected duration, not just today's date. A COI valid at the time of signing but expiring mid-project is a gap that's easy to miss until a claim happens after it lapses. For longer projects, build a reminder to request an updated COI before the current one expires.
Umbrella and excess coverage on larger projects
On projects where your contract requires higher liability limits than a sub's standard general liability policy provides, look for a separate umbrella or excess liability policy listed on the COI, with its own limit and effective dates. An umbrella policy sits on top of the underlying general liability and workers' comp policies and only pays out once those are exhausted — confirm it actually covers the same policy period and doesn't have gaps against the underlying coverage.
Waiver of subrogation — the clause most contracts require but few GCs check
Many subcontracts require a waiver of subrogation, meaning the sub's insurer gives up its right to pursue you for a claim it pays out on their behalf, even if you were partly at fault. This isn't automatic — it requires a specific endorsement on the policy, separate from additional insured status. If your contract calls for it, confirm the waiver of subrogation endorsement is actually listed on the COI rather than assuming general liability coverage includes it by default.
What to do when a COI looks incomplete
If a certificate is missing a section, shows a policy that expires before your project's expected completion, or the additional insured endorsement isn't attached, don't treat it as a formality to chase down later — request the corrected version before work starts. Subs who are genuinely covered can usually get an updated COI from their broker within a day; resistance or delay on a simple documentation request is itself useful information about how the relationship will go.
Coverage checklist before work starts
- COI issued directly from the insurer or broker, not the subcontractor
- General liability limits appropriate to project size — both occurrence and aggregate
- Workers' compensation in force if the sub has employees, or a filed exemption if not
- Additional insured endorsement in place if your contract requires it — not just certificate holder status
- Policy dates covering the full expected project duration
Doing this once instead of every hire
Reviewing a COI line by line for every prospective sub adds up fast once you're sourcing regularly. Sub-Finder's independent verification checks license, business registration, and identity for every listed subcontractor before they're even shown in search results, so the baseline diligence is already done — your own review can focus on the project-specific coverage details above.