What is a certificate of insurance (COI)?

The essentials

A COI is issued by the insurer or their broker. It lists the insured, the policy type, the coverage limits, the effective dates and any parties named as additional insured. It is not the full policy, it is the summary you share to prove cover exists. In the UK you will most often see it called a certificate of insurance, an insurance certificate or, for employers' liability, a statutory certificate that has to be displayed or made available to employees.

COI, policy schedule and policy wording: the difference

Three documents get confused constantly. The certificate proves cover exists. The schedule lists the specifics: limits, excess, endorsements and named activities. The wording is the full contract, including every exclusion. A certificate alone will not tell you whether the trade your subcontractor is about to do is actually covered.

The fields on a typical UK COI

Six checks that take two minutes

1. Insured name matches the legal entity on your contract, not the trading name on the invoice.
2. Period of insurance covers the whole engagement, not just the start date.
3. Limit of indemnity meets the minimum in your contract or your client's requirement.
4. Policy type actually matches the work. Public liability does not cover professional advice.
5. Aggregate versus any-one-claim is stated. An aggregate limit shared across a year is weaker than it looks.
6. The issuer is a real insurer or broker. A certificate that arrives as an editable Word file is a red flag.

Common ways a valid-looking certificate lets you down

Most COI failures are not forgery, they are mismatch. The entity named is a dormant holding company. The public liability policy excludes hot works or work at height. The professional indemnity is claims-made, so it covers claims notified during the policy period rather than work done during it. A lapse then creates a gap that never closes. Or the certificate is genuine but eleven months old, and nobody asked for this year's.

• Entity mismatch between certificate, contract and invoice.
• Activity exclusions buried in the schedule rather than the certificate.
• Claims-made professional indemnity with a break in cover.
• Aggregate limits already eroded by earlier claims.
• Territorial limits that exclude the site you are working on.

What to do with a COI when you receive one

File it against the supplier record, capture the expiry date, set a reminder 60 days out and check the limits meet your contract. Keep the previous certificate too, because proving continuous cover across a renewal is the thing an insurer or a client will actually ask you for. Credbase reads the expiry, files the certificate against the right supplier and sets the reminders automatically, so the only human step is a quick approval.

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