Guides
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.
The Insurance Services Office, known as ISO, publishes the standard homeowners forms that much of the industry uses as a template: the HO-3, HO-4, HO-6 and their siblings. Your policy may not be one of them. It can be an older ISO edition, an insurer's own form with similar headings and different wording, or an ISO form changed by state endorsements and company endorsements. Guides like this one describe the ISO wording because it is public and widely copied; your policy and declarations page decide what your insurer owes you.
What the ISO forms are
ISO is a Verisk business that develops insurance forms, rules and loss data for the property and casualty industry. Insurers can adopt its forms as written, modify them, or write their own. The American Association of Insurance Services (AAIS), which describes itself as the only national not-for-profit insurance advisory organization for the industry, offers a competing set of forms.
An ISO form number tells you what you hold. In HO 00 03 05 11, "HO" means homeowners, "03" identifies the HO-3 special form, and "05 11" is the edition, May 2011. The May 2011 editions of the HO-3, HO-4 and HO-6 are posted publicly by the Maine Bureau of Insurance, for example the HO-3, which makes them a handy yardstick. Each page carries ISO's 2010 copyright notice.
The family covers the types in Homeowners policy types: HO-1 through HO-8 explained: HO-3 for owner-occupied houses, HO-4 for renters and HO-6 for condo unit owners are the three most people meet.
Who actually uses ISO wording
The Maine Bureau of Insurance publishes sample policies from the ten largest homeowners groups in the state, based on 2022 market share data (Maine Bureau of Insurance). The list shows the variety:
- Some groups file ISO's May 2011 edition (HO 00 03 05 11).
- Others still file older ISO editions dated 04 91 and 10 00.
- Others file forms under their own titles and numbers.
The table also has a column for Maine amendatory endorsements and a note that other forms and endorsements that are part of the contract may affect your specific coverage.
Five reasons your policy may differ
1. It is the insurer's own form. Proprietary forms may rearrange sections, add features such as higher built-in limits, or define terms differently. They may also include provisions that ISO's form does not, such as separate wind and hail terms.
2. It is an older edition. The edition date appears in the footer. Insurers update on their own schedules, and older editions with different wording remain in use. The 2011 form, for example, contains an ordinance or law additional coverage of up to 10% of the dwelling limit, and you cannot assume an older edition says the same.
3. State law rewrites it. Insurers attach a state amendatory endorsement, also called a special provisions endorsement, to conform the form to local statutes and regulations. That is how state law gets into your contract, and it overrides the base wording where they conflict. The table below shows how far it can move.
4. Endorsements change it. The declarations page lists the endorsements attached to your policy. An endorsement can add coverage, such as scheduled jewelry or water backup, or take it away, such as a wind exclusion, an actual cash value roof clause or a cosmetic damage exclusion. See endorsements, riders and floaters: what the words mean.
5. The declarations page fills in the blanks. The form states formulas and caps, and the declarations page supplies the numbers: limits, deductibles, mortgagee and policy period.
The same clause, different rules
Take a few provisions where the ISO HO-3 states one rule and public sources show states doing something else.
| Topic | ISO HO 00 03 05 11 | Examples of state rules |
|---|---|---|
| Time to sue your insurer | Suit must start within two years after the date of loss | California: 12 months from the inception of the loss, or 24 months for state-of-emergency losses (Cal. Ins. Code §2071, per the California Department of Insurance). Florida: a five-year statute of limitations for property insurance contract suits from the date of loss, plus a one-year deadline to give notice of a claim (Fla. Stat. §§95.11(2)(e), 627.70132). Texas: a contract cannot shorten the period to less than two years (Tex. Civ. Prac. & Rem. Code §16.070) |
| Notice of nonrenewal | At least 30 days before expiration | Florida: 120 days with the reason. California: 75 days. Texas: 60 days for policies bought or renewed in 2024, per the Texas Department of Insurance |
| Actual cash value | Not defined in the form | California: fair market value on a total loss |
| Appraisal | Either side may demand it | California: in a government-declared disaster, appraisal may be requested but not compelled |
Sources for the state rows: Fla. Stat. §95.11, §627.70132 and §627.4133; the California Department of Insurance homeowners guide and its 2026 guide for adjusting property claims; Tex. Civ. Prac. & Rem. Code ch. 16; and the Texas Department of Insurance home insurance guide. Two homeowners with "an HO-3" in different states can therefore have different deadlines even if the base form matches word for word. The deadlines to sue over a home insurance claim guide covers the suit clause in depth, and home insurance rules by state points to your state's rules.
Two ISO clauses worth knowing
Waiver or change of policy provisions. The ISO form says a waiver or change must be in writing by the insurer to be valid. A producer's verbal assurance that "that's covered" does not change the contract. Get it in an endorsement or the declarations.
The liberalization clause. If the insurer broadens coverage under the current edition without charging more, and implements the change in your state within 60 days before or during your policy period, the broader coverage applies to you automatically. The clause does not apply to a general program revision that includes both broadenings and restrictions.
Who checks the forms
Insurers file policy forms with state insurance departments, and states differ on whether a regulator must approve a form before it can be used. The departments handle complaints, and some post filed forms or sample policies for consumers, as Maine does. If a provision looks like it conflicts with your state's law, a complaint to the department is an option. See who regulates homeowners insurance? and how to file a complaint with your state insurance department.
How to find out what you actually have
- Find the list of forms and endorsements on the declarations page and write down each form number and edition.
- Ask your agent or insurer for a complete copy of the policy, including every endorsement and the state amendatory endorsement.
- If the base form is an ISO number, read the matching public ISO text next to it, such as the Maine-hosted PDFs, and mark the differences.
- Read endorsements last, since they override the base form where they conflict.
- Look for your state's special provisions on cancellation, nonrenewal, suit deadlines and claim timelines.
- For anything that matters to a decision, ask for the answer in writing from the insurer.
The which homeowners policy form fits your home? helps if you are not sure which form fits your home, and how to read your homeowners policy, section by section walks through the sections.
Key takeaways
- ISO writes the standard homeowners forms, but insurers can adopt, edit or replace them; the Maine Bureau of Insurance's sample policies show all three.
- The form number and edition on your declarations page identify what you hold: HO 00 03 05 11 is the HO-3, May 2011 edition.
- State amendatory endorsements override the base form, and deadlines such as nonrenewal notice and time to sue differ by state.
- Endorsements and the declarations page can add, remove or size coverage, so read the whole package.
- A verbal promise from an agent does not change the policy; the ISO form requires a written change.