What is an insurance endorsement?

An amendment to the base policy

An insurance policy starts as a standardized base form, but few risks fit that form exactly. An endorsement(sometimes called a rider) is a written amendment attached to the policy that changes its terms—it can add coverage, remove or exclude coverage, or modify how the policy works. Once attached, the endorsement becomes part of the policy contract and is just as binding as the base form.

Each standard endorsement has a form number and edition date— for example, “CG 20 10 04 13.” Those identifiers matter, because different editions of the same form can grant meaningfully different coverage. When a contract calls for a specific form and edition, only that exact endorsement satisfies it.

Common construction endorsements

A handful of endorsements do most of the work of risk transfer between a general contractor and its subcontractors:

• Additional insured—CG 20 10 (ongoing operations) and CG 20 37 (completed operations) add the GC to the sub’s general liability policy so it responds on the GC’s behalf.
• Waiver of subrogation—the sub’s insurer gives up its right to recover from the GC after paying a claim; commonly required on both general liability and workers’ comp.
• Primary and non-contributory—CG 20 01 makes the sub’s policy pay first, without seeking contribution from the GC’s policy.

Other endorsements adjust limits and structure—such as the per-project aggregateendorsements (CG 25 03 / CG 25 04) that keep one project’s claims from eroding another’s coverage.

The key point: a checkbox is NOT proof

This is the most important thing a GC can understand about endorsements. A checked box or a note in the description field of a certificate of insurance is not proof that the endorsement exists. The ACORD 25says so in bold: it is issued as information only, confers no rights, and “does not amend, extend, or alter” the coverage. The checkbox is just the broker’s summary of what is supposed to be on the policy.

Coverage lives in the policy, and the endorsement formis what proves a feature actually applies. A certificate can show an additional insured box checked when no additional insured endorsement was ever attached—whether through error or worse—and the GC would only discover the gap when a claim is denied.

Why GCs should request the actual endorsement forms

Because the certificate only summarizes coverage, careful general contractors require more than a COI for the endorsements that matter. Best practice is to request:

• Copies of the actual endorsement forms—identified by form number and edition date—for additional insured, waiver of subrogation, and primary and non-contributory.
• Or, for the highest-risk relationships, the relevant pages of the full policy.
• Confirmation the edition dates match what the subcontract requires, since editions differ in scope.

Reviewing endorsement forms—not just certificates—is what turns a contractual insurance requirement into coverage you can actually rely on.

How does Wardly help?

Wardly is free COI tracking software built for general contractors. It reads each subcontractor’s certificate, checks that the additional insured, waiver of subrogation, and primary and non-contributory requirements you set are reflected, flags what’s missing, and lets you collect the supporting endorsement documents in one place—grading every certificate A–F automatically. Compare it to myCOI and TrustLayer on the comparison hub.

This is general information, not legal or insurance advice.