Glossary

ISO (Insurance Services Office)

The industry organization, now part of Verisk, that drafts standard homeowners policy forms, rating data and fire protection grades that insurers use or adapt.

Also called: Insurance Services Office, ISO forms, Verisk

ISO, the Insurance Services Office, develops standard insurance forms, statistics and rating information for property and casualty insurers. It is now part of Verisk. ISO is not a regulator and does not sell insurance; state insurance departments regulate rates and forms. Its homeowners forms, such as HO 00 03, are the reference most agents and adjusters learn, and the form numbers on a declarations page, like HO 04 61 for scheduled property, usually come from its catalog.

Insurers choose how to use the catalog. Some adopt ISO forms as filed, some file them with changes, and many large carriers write their own policies, so your wording can differ from the standard text. ISO dates its editions by month and year, for example 05 11 and 03 22. A form marked 05 11 is the May 2011 edition. ISO homeowners forms and why your policy may differ explains why that matters when you compare a quote with a published description.

ISO also grades communities' fire protection on a scale of 1 to 10, the Public Protection Classification that many insurers use in rating. Homeowners usually meet ISO through those numbers or through a state-specific amendatory endorsement that adapts the base form to local law.

Last reviewed October 10, 2026

In the index now

Related terms

Amendatory endorsement An add-on that rewrites parts of the base policy, usually to match a state's insurance laws, and that takes priority wherever it conflicts with the form. Endorsement A written change attached to a policy that adds, removes or alters coverage, limits or conditions, and controls over the base form wherever the two conflict. Public Protection Classification (PPC) A 1 to 10 grade, assigned by Verisk's ISO unit, of how well a community's fire department, water supply and dispatch can fight a house fire. Declarations page The summary page at the front of a policy listing the insured, the property, policy dates, limits, deductibles, premium, mortgage lender and attached forms. HO-3 (special form) The most common homeowners policy: open-perils coverage for the house and other structures, and named-perils coverage for belongings.

Related guides

Golf carts, boats and ATVs under a homeowners policy A standard HO-3 pays almost nothing for damage to golf carts, ATVs and boats, and its liability cover has speed, horsepower and location limits. Know the gaps. HO-8 policies for older homes The HO-8 is a named-perils form that pays to repair an older home with common modern materials, not to restore its original plaster, tile and trim. Homeowners policy types: HO-1 through HO-8 explained What each HO form covers, who can buy it, how many policies use it, and how to find the form on your own declarations page. How to read your homeowners policy, section by section Read the declarations page and endorsements first, then definitions, Section I, Section II and conditions. A tour of the ISO HO-3 layout and its deadlines. ISO homeowners forms and why your policy may differ ISO publishes the standard homeowners forms, but your policy may use an older edition, an insurer's own wording or state endorsements. How to tell. What is homeowners insurance and how does it work Homeowners insurance pays to repair your house, replace belongings and cover your liability to others. How premiums, limits, deductibles and claims fit.