Endorsement Form Numbers

Overview

Endorsement Form Numbers are standardized alphanumeric identifiers published by ISO (Insurance Services Office) that uniquely name individual policy endorsements. A form number like CG 20 10 is not just a label — it pins down the exact wording of the endorsement, which in turn pins down the precise scope of coverage granted.

Because an endorsement modifies a policy's base coverage, and because commercial contracts frequently require specific endorsements by number, form number accuracy is compliance-critical. Saying "the policy provides additional insured coverage" is meaningless; saying "per CG 20 10 04 13" identifies a specific ISO form with known language, effective date, and legally tested scope.

The numbering convention follows the pattern [Line] [Function] [Sequence] [Edition] — e.g., CG (Commercial General Liability) 20 (Additional Insured section) 10 (specific form) 04 13 (April 2013 edition).

How It Works

When a producer issues a COI, the Description of Operations should reference endorsements by form number:

"Additional Insured per CG 20 10 04 13 and CG 20 37 04 13. Waiver of Subrogation per CG 24 04 05 09. Primary and Non-Contributory per CG 20 01 04 13."

Each form has a precise, legally interpreted meaning:

• CG 20 10 — Additional Insured for ongoing operations only.
• CG 20 37 — Additional Insured for completed operations.
• CG 20 26 — Additional Insured — Designated Person or Organization (broadest AI form).
• CG 24 04 — Waiver of Transfer of Rights of Recovery Against Others to Us (Waiver of Subrogation).
• CG 20 01 — Primary and Non-Contributory — Other Insurance Condition.
• CG 25 03 — Designated Construction Project(s) General Aggregate Limit (Per Project).
• CG 25 04 — Designated Location(s) General Aggregate Limit (Per Location).

The edition date matters: CG 20 10 10 01 (October 2001) provided broader coverage than CG 20 10 04 13 (April 2013), which narrowed AI status in important ways (e.g., requiring a written contract executed before the loss). Certificate holders with strict requirements should specify not just the form number but also the acceptable edition date.

Reference Table of Common Forms

Similar conventions exist for other lines: CA for Commercial Auto, CP for Commercial Property, WC for Workers' Compensation, CU for Commercial Umbrella.

On the COI / Where it appears on ACORD 25

Endorsement form numbers do not have a dedicated field on the ACORD 25. They appear as free-text references in the Description of Operations block, typically following descriptive phrases like "per CG 20 10" or "as per endorsement CG 24 04." Longer endorsement lists that exceed the DoO space are usually routed to an attached ACORD 101 schedule.

A COI that claims additional insured or waiver-of-subrogation coverage without naming the specific form number is weaker evidence than one that names the form — the form number is what a claims examiner will ask for at the moment of loss.

Why It Matters for Compliance

• Precision verification: Inori parses description_of_operations for ISO-pattern form numbers (regex matching [A-Z]{2} \d{2} \d{2}(?: \d{2} \d{2})?) and stores them in provisions.endorsement_forms_mentioned. The compliance engine then verifies that each contract-required form is present.
• Edition-date sensitivity: When contracts specify "CG 20 10 11 85 or broader," Inori compares the edition date against known ISO versions and flags narrower editions.
• Phantom coverage detection: A COI with ADDL INSD marked but no CG 20 10 / CG 20 37 / CG 20 26 reference in the DoO is flagged — the checkbox alone is not verifiable evidence of the underlying endorsement.
• Cross-line normalization: The engine recognizes that WC 00 03 13 serves the same function (waiver of subrogation) on a WC policy as CG 24 04 on a GL policy and evaluates them in parallel when matching contract requirements.

Related Concepts

Endorsement Form Numbers are the precise identifiers for the Endorsement provisions that modify base policy coverage. They most frequently document Additional Insured status, Waiver of Subrogation grants, and per-project aggregate selections. They appear primarily in the Description of Operations on the ACORD 25 and relate to the base General Liability or Auto policy being modified.