ISO Commercial Lines Forms Explained
Every commercial insurance policy is built on forms — standardized documents that define what is and is not covered. The Insurance Services Office (ISO), now part of Verisk, develops and maintains the most widely used commercial insurance forms in the United States. When you hear an underwriter reference "CG 00 01" or "CP 00 10," they are referring to specific ISO form numbers that define coverage terms, conditions, and exclusions.
Understanding ISO forms is foundational knowledge for commercial lines agents. The forms determine what coverage the client actually has — not the declarations page, not the marketing materials, not the verbal promises. The form is the contract. Knowing how to identify forms, understand their numbering system, read edition dates, and recognize the most important endorsements makes you a more effective agent and reduces your errors and omissions exposure.
This guide covers the ISO form numbering system, the key commercial property forms, general liability forms, commercial auto forms, essential endorsements, the difference between ISO and manuscript forms, and how to read form edition dates. For agents who work extensively with ACORD forms (the application and certificate forms), this is the other half of the equation — ACORD forms are what you submit; ISO forms are what the carrier issues.
TLDR: ISO commercial lines forms use a standardized numbering system: the first two letters identify the coverage line (CP = commercial property, CG = commercial general liability, CA = commercial auto), the next two digits indicate the form type, and the final two digits identify the specific form. Key forms every agent should know include CP 00 10 (building and personal property), CG 00 01 (occurrence GL), CG 00 02 (claims-made GL), and CA 00 01 (business auto). Edition dates matter — form language changes with each edition, and knowing which edition is on the policy determines the actual coverage in force.
The ISO Form Numbering System
ISO forms follow a consistent naming convention that, once understood, makes it possible to quickly identify what any form does.
The Structure
Every ISO form number has three components:
| Component | What It Identifies | Example |
|---|---|---|
| Two-letter prefix | The line of business | CG = Commercial General Liability |
| First two digits | The form category (coverage form, conditions, definitions, endorsement) | 00 = coverage form; 20 = endorsement |
| Last two digits | The specific form within that category | 01 = occurrence form; 02 = claims-made form |
Example: CG 00 01 breaks down as:
- CG — Commercial General Liability line
- 00 — Coverage form category
- 01 — Occurrence form
Common Line Prefixes
| Prefix | Line of Business |
|---|---|
| CP | Commercial Property |
| CG | Commercial General Liability |
| CA | Commercial Auto |
| CF | Commercial Fire (monoline fire policy) |
| CM | Commercial Inland Marine |
| CR | Commercial Crime |
| IL | Interline (applies across multiple lines) |
| IM | Inland Marine |
| WC | Workers Compensation |
Form Categories
The first two digits after the prefix indicate the type of document:
| Digits | Category | Purpose |
|---|---|---|
| 00 | Coverage forms | The core policy forms that define insuring agreements, exclusions, and conditions |
| 01–09 | Declarations pages and schedules | The customizable pages that identify the insured, limits, premiums, and scheduled items |
| 10 | Conditions | Policy conditions that apply to the coverage line |
| 20–29 | Endorsements | Modifications to the coverage form — adding, removing, or changing coverage |
| 30–39 | Endorsements (continued) | Additional endorsement series |
| 99 | Miscellaneous | Various forms that don't fit other categories |
Key Commercial Property Forms
Commercial property insurance is built on a modular system. The coverage form, the causes of loss form, and the conditions form work together to create the complete policy. Understanding each component is essential for agents.
CP 00 10 — Building and Personal Property Coverage Form
This is the most commonly used commercial property coverage form. It defines three categories of covered property:
Coverage A — Building: The building itself, including completed additions, permanently installed fixtures, machinery and equipment (used to maintain or service the building), outdoor fixtures, and personal property used to maintain or service the building.
Coverage B — Business Personal Property: Property the insured owns that is used in the business — furniture, equipment, stock/inventory, and leasehold improvements (tenant improvements and betterments) if the tenant made and paid for them.
Coverage C — Personal Property of Others: Property owned by others that is in the insured's care, custody, or control.
Key provisions agents should understand:
- Coinsurance — the property must be insured to a specified percentage of its full value (typically 80%, 90%, or 100%). If the insured underinsures the property, the coinsurance penalty reduces claim payments proportionally.
- Agreed value — suspends the coinsurance clause when the insured provides a signed statement of values and the carrier agrees to the amount. This is preferable to coinsurance for most accounts.
- Valuation — CP 00 10 provides actual cash value (ACV) as the default valuation method. Replacement cost coverage requires the CP 99 30 endorsement or the inclusion of replacement cost language.
CP 00 30 — Business Income (and Extra Expense) Coverage Form
This form covers the loss of business income and extra expenses incurred when a covered property loss forces the business to suspend operations.
Business income = Net income (or loss) + continuing normal operating expenses (including payroll).
Extra expense = Costs incurred to avoid or minimize a shutdown — renting temporary space, leasing replacement equipment, expediting repairs.
Critical provisions:
- Period of restoration — coverage runs from the time of the loss until the property is repaired/replaced and operations resume (or should have resumed with reasonable speed). This is not a fixed time period — it is based on the actual time needed to restore operations.
- Extended business income — optional extension that covers the continued loss of income after the property is restored but before revenue returns to pre-loss levels. This recognizes that customers may not return immediately.
- Civil authority coverage — covers business income loss when a governmental authority prohibits access to the insured premises due to a covered peril at a neighboring property. Standard coverage period is typically limited (often 4 weeks, expandable by endorsement).
- 72-hour waiting period — standard forms include a 72-hour waiting period before business income coverage begins. This can be reduced or eliminated by endorsement.
CP 00 40 — Legal Liability Coverage Form
This form covers the insured's legal liability for damage to buildings and personal property of others when the insured is a tenant or has care, custody, or control of the property. It responds when the insured is legally liable for property damage — not when the insured owns the property.
Common use case: Tenants who are contractually required to insure the building owner's property against damage caused by the tenant's negligence. This is different from the tenant's own property (covered under CP 00 10 Coverage B) and different from the building owner's property coverage.
Causes of Loss Forms
The CP 00 10 coverage form defines what property is covered. The causes of loss form defines what perils are covered. ISO provides three options:
| Form | Name | What It Covers |
|---|---|---|
| CP 10 10 | Causes of Loss — Basic Form | Fire, lightning, explosion, windstorm/hail, smoke, aircraft/vehicles, riot, vandalism, sprinkler leakage, sinkhole collapse, volcanic action |
| CP 10 20 | Causes of Loss — Broad Form | Everything in Basic + falling objects, weight of snow/ice/sleet, water damage (from plumbing, HVAC, appliances) |
| CP 10 30 | Causes of Loss — Special Form | All risks of direct physical loss unless specifically excluded. This is the broadest coverage and the form most commonly used for commercial accounts. |
Key distinction: Basic and Broad are "named perils" forms — they list specific covered perils, and if the peril is not listed, it is not covered. Special is an "open perils" form — it covers everything unless specifically excluded. The Special form is significantly broader and is the standard recommendation for most commercial accounts.
Major exclusions in CP 10 30 (Special Form):
- Ordinance or law (available by endorsement)
- Earth movement (earthquake — available by endorsement)
- Flood (available through NFIP or private flood markets)
- Government action
- Nuclear hazard
- War and military action
- Utility services failure originating off premises
- Wear and tear, deterioration
- Insects, vermin, rodents
- Mechanical breakdown (available through equipment breakdown coverage)
Key General Liability Forms
CG 00 01 — Commercial General Liability Coverage Form (Occurrence)
This is the most important form in commercial insurance. The CG 00 01 occurrence form provides general liability coverage for bodily injury and property damage claims based on when the occurrence (the event causing the injury or damage) takes place — regardless of when the claim is actually filed.
Coverage sections:
| Section | Coverage | What It Insures |
|---|---|---|
| Coverage A | Bodily Injury and Property Damage Liability | Third-party injuries and property damage caused by the insured's operations or products |
| Coverage B | Personal and Advertising Injury Liability | Defamation, slander, libel, false arrest, wrongful eviction, copyright infringement in advertising |
| Coverage C | Medical Payments | Small medical expense payments for third-party injuries on premises, regardless of fault |
Key exclusions in CG 00 01:
- Expected or intended injury — intentional acts are not covered
- Contractual liability — excluded, except for "insured contracts" (which includes most common contractual assumptions of liability, making this exclusion narrower than it appears)
- Liquor liability — for businesses in the business of selling/serving alcohol
- Workers compensation and similar laws — employee injuries are a WC exposure, not GL
- Pollution — the absolute pollution exclusion eliminates most environmental liability (a few narrow exceptions apply)
- Aircraft, auto, and watercraft — covered under separate policies
- Damage to your product — if your product itself is defective, the cost of the defective product is not covered (but damage the product causes to other property is covered)
- Damage to your work — similar to damage to your product, but for completed construction work
- Damage to impaired property — property that is unusable because the insured's product or work is defective, where the property can be restored by repair, replacement, or removal of the insured's product/work
- Product recall — the cost of recalling a defective product is excluded
Understanding the "your work" exclusion: For contractors, the CG 00 01 excludes damage to the insured's own completed work. However, the subcontractor exception (Exclusion l. of Coverage A) reinstates coverage for damage to the named insured's work if the damage is caused by a subcontractor's portion of the work. This exception is critical for general contractors — without it, a GC would have no GL coverage for damage to their completed project caused by a subcontractor's faulty work.
CG 00 02 — Commercial General Liability Coverage Form (Claims-Made)
The claims-made form provides coverage based on when the claim is first made (reported), not when the occurrence happened. This form requires understanding several additional concepts:
- Retroactive date — the policy only covers claims arising from occurrences that happen on or after this date. Occurrences before the retroactive date are not covered, even if the claim is first made during the policy period.
- Extended reporting period (tail) — if the policy is cancelled or not renewed, the insured can purchase an extended reporting period that allows claims to be reported after the policy ends (for occurrences that happened during the policy period).
- Prior acts coverage — if the retroactive date is set to "full prior acts" (no retroactive date), the policy covers claims from occurrences that happened at any time — as long as the claim is first made during the policy period.
When claims-made GL is used: Claims-made is less common than occurrence for standard GL but is standard for professional liability (E&O) and employment practices liability (EPLI). Some carriers also write GL on a claims-made basis for specific high-risk classes. For a deeper discussion of the differences, see our guide on occurrence vs. claims-made policies.
Commercial Auto Forms
CA 00 01 — Business Auto Coverage Form
The CA 00 01 is the standard commercial auto form. It provides liability and physical damage coverage for business-owned vehicles. The key feature of this form is the covered auto designation system, which controls which vehicles are covered.
Covered auto designation symbols:
| Symbol | Description | What It Covers |
|---|---|---|
| 1 | Any auto | All autos, including owned, hired, non-owned, and borrowed |
| 2 | Owned autos only | Vehicles titled in the named insured's name |
| 3 | Owned private passenger autos only | Owned autos that are private passenger vehicles |
| 4 | Owned autos other than private passenger autos only | Owned trucks, vans, and specialty vehicles |
| 5 | Owned autos subject to no-fault | Owned autos registered in no-fault states |
| 6 | Owned autos subject to compulsory uninsured motorist law | Owned autos in states requiring UM coverage |
| 7 | Specifically described autos | Only vehicles listed on the schedule |
| 8 | Hired autos only | Vehicles the insured rents, leases, or borrows |
| 9 | Non-owned autos only | Vehicles owned by employees or others used for insured's business |
Key point for agents: Symbol 1 (any auto) provides the broadest coverage and is the recommended selection for most businesses. Using symbols 7 (specifically described) or 2 (owned autos only) can create gaps — if the insured acquires a new vehicle and forgets to add it to the schedule, it may not be covered. Symbol 1 automatically covers new acquisitions without requiring an endorsement.
Physical damage coverage:
- Comprehensive — covers loss from any cause except collision. Includes theft, fire, flood, vandalism, glass breakage, falling objects, and animal collisions.
- Collision — covers loss from collision with another object or vehicle, including rollover.
- Specified causes of loss — a narrower alternative to comprehensive that covers only listed perils (fire, lightning, explosion, theft, windstorm, hail, earthquake, flood, mischief/vandalism).
Key Endorsements Every Agent Should Know
Endorsements modify the base coverage form — adding coverage, removing exclusions, or changing terms. These are the endorsements that come up most frequently in commercial lines practice.
General Liability Endorsements
| Form | Name | What It Does |
|---|---|---|
| CG 20 10 | Additional Insured — Owners, Lessees, or Contractors (Scheduled) | Adds a scheduled entity as additional insured for ongoing operations |
| CG 20 37 | Additional Insured — Owners, Lessees, or Contractors (Completed Operations) | Adds additional insured status for completed operations claims |
| CG 20 11 | Additional Insured — Managers or Lessors of Premises | Adds building owners/managers as additional insured for premises liability |
| CG 20 26 | Additional Insured — Designated Person or Organization | Blanket additional insured for any entity required by written contract |
| CG 20 33 | Additional Insured — Owners, Lessees, or Contractors (Automatic Status) | Automatically adds additional insured when required by written contract |
| CG 24 04 | Waiver of Transfer of Rights of Recovery Against Others to Us | Waiver of subrogation endorsement |
| CG 25 03 | Designated Construction Project(s) General Aggregate Limit | Provides separate aggregate for each construction project |
| CG 25 04 | Designated Location(s) General Aggregate Limit | Provides separate aggregate for each business location |
| CG 21 47 | Employment-Related Practices Exclusion | Excludes all employment-related claims from GL (standard in many carriers' programs) |
| CG 21 67 | Fungi or Bacteria Exclusion | Excludes mold and bacteria claims |
| CG 00 33 | Liquor Liability Coverage Form | Provides liquor liability coverage for alcohol-serving businesses |
Commercial Property Endorsements
| Form | Name | What It Does |
|---|---|---|
| CP 99 30 | Causes of Loss — Special Form Endorsement | Endorses replacement cost valuation onto the policy |
| CP 04 01 | Protective Safeguards | Requires the insured to maintain specified protective safeguards (sprinklers, alarms, etc.) |
| CP 01 40 | Ordinance or Law Coverage | Covers the increased cost of rebuilding to comply with current building codes |
| CP 10 32 | Water Exclusion Endorsement | Modifies or restricts water damage coverage |
| CP 04 18 | Peak Season Limit of Insurance | Allows higher limits during peak inventory seasons |
| CP 12 18 | Loss Payable Provisions | Specifies how loss payments are made when a mortgagee or loss payee has an interest |
Commercial Auto Endorsements
| Form | Name | What It Does |
|---|---|---|
| CA 99 47 | Employee as Insured | Extends liability coverage to employees while using their own vehicles for business |
| CA 20 48 | Designated Insured | Adds additional insured status on the auto policy |
| CA 20 01 | Broad Form Products Coverage | Extends auto coverage to products transported by covered vehicles |
| MCS-90 | Motor Carrier Endorsement | Required for for-hire trucking operations; provides financial responsibility under federal motor carrier regulations |
How to Read Form Edition Dates
Every ISO form includes an edition date — the date the current version of the form was published by ISO. Edition dates matter because form language changes between editions, and those changes can significantly affect coverage.
Where to Find the Edition Date
The edition date appears in the lower-left corner of the form, typically in the format "CG 00 01 04 13" — where "04 13" indicates the April 2013 edition.
Why Edition Dates Matter
ISO periodically revises its forms to address court decisions, industry developments, and coverage issues. Each revision can add or remove coverage. A few significant examples:
CG 00 01 editions:
- 1986 edition — the "original" modern CGL form. Introduced the absolute pollution exclusion and the "expected or intended" exclusion.
- 1996 edition — added the "mobile equipment" exception to the auto exclusion. Modified the "your work" exclusion.
- 2001 edition — significant revision to the additional insured endorsement provisions. Limited additional insured coverage to claims "caused in whole or in part" by the named insured's acts or omissions.
- 2004 edition — added terrorism exclusion language.
- 2013 edition — current widely used edition. Modified personal and advertising injury coverage, revised the definition of "insured contract," and updated numerous endorsements.
Key point: When reviewing a certificate of insurance or a policy, always check the edition date on the CGL form. A policy issued in 2026 could be using the 2013 edition of CG 00 01 (or even an earlier edition if the carrier has not adopted the latest version). The edition date determines the actual coverage terms — not the policy effective date.
Carrier Adoption of ISO Editions
Not all carriers adopt new ISO editions at the same time. Some carriers adopt new editions within months of ISO publishing them. Others continue using older editions for years. A few carriers never fully adopt certain ISO editions and instead use their own proprietary modifications.
This means two policies both labeled "CG 00 01" may provide different coverage if they use different edition dates. When comparing quotes from multiple carriers, checking edition dates is one of the ways to compare coverage on an apples-to-apples basis.
ISO Forms vs. Manuscript Forms
ISO Forms
ISO forms are standardized, widely used, and well-understood by agents, underwriters, claims adjusters, and courts. The advantages of ISO forms include:
- Predictability — courts across the country have interpreted ISO form language extensively, creating a large body of case law that makes coverage outcomes more predictable
- Comparability — when two policies use the same ISO form, comparing coverage is straightforward because the base language is identical
- Agent familiarity — most commercial lines training is built around ISO forms, so agents can identify coverage and gaps quickly
Manuscript Forms
Manuscript forms are proprietary forms drafted by individual carriers. They may be loosely based on ISO forms or entirely custom. Manuscript forms are common in specialty lines, excess and surplus markets, and for specific programs.
Advantages of manuscript forms:
- Can provide broader coverage than ISO in specific areas
- Can be tailored to specific industries or risk profiles
- May fill gaps that ISO forms do not address
Risks of manuscript forms:
- Less court interpretation — coverage outcomes are less predictable
- Harder to compare between carriers — the language differs, making apples-to-apples comparison difficult
- Agent unfamiliarity — agents must read manuscript forms carefully because they cannot rely on their knowledge of ISO form language
- Hidden restrictions — some manuscript forms appear similar to ISO but contain narrower terms in critical areas
Best practice for agents: When evaluating a quote that uses manuscript forms, compare the manuscript language to the equivalent ISO form provision by provision. Identify where the manuscript form is broader (a selling point for the client) and where it is narrower (a potential coverage gap). Document your analysis — this protects both the client and your agency from E&O claims.
How Agents Use ISO Form Knowledge
Understanding ISO forms provides practical advantages in day-to-day agency work.
Quote Comparison
When comparing quotes from multiple carriers, identify the forms used in each quote. If all carriers are using the same ISO forms, the coverage comparison focuses on limits, deductibles, pricing, and endorsements. If some carriers use manuscript forms, a line-by-line comparison of coverage terms is necessary. Pair your form analysis with the account's loss run history to understand how prior claims interact with the coverage terms each carrier is offering.
Coverage Gap Analysis
Knowing what the standard ISO forms exclude allows agents to identify gaps and recommend endorsements proactively. For example:
- CP 10 30 (Special Form) excludes ordinance or law — recommend CP 01 40
- CG 00 01 excludes pollution — recommend a pollution liability endorsement or standalone policy for applicable accounts
- CP 00 10 defaults to ACV — recommend replacement cost valuation for most accounts
Claims Advocacy
When a claim is filed, the form determines coverage. Agents who understand form language can advocate for their clients by pointing to specific provisions that support coverage. Agents who do not understand the forms are at the mercy of the adjuster's interpretation.
Certificate Verification
When reviewing certificates of insurance for contract compliance, understanding ISO form numbers allows agents to verify that the required endorsements are actually in place. A certificate that lists "CG 20 10" as an endorsement tells you that additional insured coverage for ongoing operations has been endorsed — but you should also look for CG 20 37 (completed operations) if the contract requires it.
Frequently Asked Questions
What is the difference between CG 00 01 and CG 00 02?
CG 00 01 is the occurrence-based commercial general liability form — it covers claims based on when the injury or damage occurred, regardless of when the claim is filed. CG 00 02 is the claims-made form — it covers claims based on when the claim is first reported to the insurer, subject to a retroactive date. Occurrence policies are more common for standard GL accounts. Claims-made policies are standard for professional liability and are sometimes used for specific high-risk GL classes.
How do I find out which ISO edition a carrier is using?
Check the policy forms themselves — the edition date appears in the lower-left corner of each form. If you are reviewing a quote before binding, ask the underwriter which edition of each form the policy will include. You can also check the carrier's filed forms with the state insurance department, as carriers must file the forms they use in each state.
Are all carriers required to use ISO forms?
No. Carriers can use ISO forms, modify ISO forms with proprietary endorsements, or develop their own manuscript forms. ISO forms are the most common in the standard/admitted market, but surplus lines carriers and specialty programs frequently use manuscript forms. Some carriers use "ISO-based" forms that start with the ISO language but modify key provisions.
What is the most important ISO endorsement for contractors?
The additional insured endorsements — particularly CG 20 10 (ongoing operations) and CG 20 37 (completed operations). Virtually every construction contract requires the subcontractor to add the general contractor and project owner as additional insureds. Without these endorsements, the subcontractor's policy does not extend coverage to the GC/owner for claims arising from the subcontractor's work.
How often does ISO update its forms?
ISO does not follow a fixed update schedule. Major form revisions occur every several years, while individual endorsements may be added, revised, or withdrawn more frequently. ISO files form changes with state insurance departments, and each state must approve the changes before carriers can use them. This means the effective date of a form change can vary by state.
