Glossary

ISO (Insurance Services Office)

The Verisk business that publishes the standard commercial policy forms, rules, classifications and loss costs most U.S. property and casualty insurers use.

Also called: ISO, Insurance Services Office, Verisk ISO, ISO forms

ISO, the Insurance Services Office, is part of Verisk. It is not a regulator and has no power over what you buy. It is an advisory organization that insurers subscribe to. ISO drafts standard policy forms and endorsements, publishes rating rules and classifications, and collects statistics from which it develops advisory loss costs. The forms are the reason policies from different carriers read alike: CG 00 01 for commercial general liability, CP 00 10 for building and personal property, CA 00 01 for business auto, and the CG 20 10 and CG 20 37 additional insured endorsements.

Insurers use ISO forms as written, modify them or file their own. ISO announces changes through circulars. Circular LI-GL-2026-208 (July 14, 2026) revised the multistate CGL forms package for policies written on or after October 1, 2026 in 48 jurisdictions, per Property Casualty 360's circular tracker. A form's edition date, such as 04 13 for April 2013, tells you which version you have, and editions differ in ways that matter at claim time.

Do not confuse it with the International Organization for Standardization, whose ISO standards cover quality management. Workers' compensation is the main line where another organization leads: NCCI publishes its forms and classifications in most states. Because so many policies share ISO wording, court rulings on one insurer's CGL often carry over. The guide on ISO forms and why most commercial policies look alike shows how to read the forms, and endorsement explains how they get modified.

Last reviewed October 10, 2026

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Related terms

Endorsement A written amendment to an insurance policy that adds, removes or changes coverage, limits or conditions, and controls over the base form where they conflict. Manuscript policy An insurance policy whose wording is drafted or heavily negotiated for one insured rather than taken from a standard ISO or insurer form. Class code The numeric code that classifies a business's operations for rating, setting the workers' compensation rate per $100 of payroll. NCCI The National Council on Compensation Insurance, the rating and data organization behind workers' comp class codes, loss costs and mods in most states. Declarations page The front section of a policy that names the insured, policy period, covered locations or operations, limits, deductibles, premium and the forms attached.

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