Understanding Blanket Additional Insured Coverage Scope for Insurance Brokers

Blanket additional insured coverage scope is the most misunderstood element of commercial GL endorsements. Clients assume AI coverage is broad. Contracts demand coverage that standard ISO forms do not provide. Agents issue certificates without confirming whether the scope matches the requirement. Claims happen. Tenders get denied. E&O exposure follows.

This post defines exactly what blanket AI covers and what it excludes, maps scope across the four most common AI endorsement forms, and gives you a framework for identifying and disclosing coverage gaps before they become claims.

Key Takeaways

• Blanket AI covers liability arising out of the named insured's operations only; it does not cover the AI's own independent negligence (ISO 2024).
• CG 20 33 covers ongoing operations only; CG 20 37 covers completed operations only; together they provide the broadest available AI scope for construction accounts.
• Additional insureds share the named insured's policy limits and do not receive separate per-occurrence limits under any standard ISO AI form.
• IIABA 2025 data: approximately 25% of AI-related coverage disputes involve a contract requiring broader AI coverage than the endorsement actually provides.
• The contract vs. policy gap is the leading source of AI-related E&O claims; agents who review AI contract language before placement close this gap proactively.
• Standard ISO AI forms do not cover the AI's sole negligence; contracts demanding this coverage cannot be satisfied by standard market forms.

What Blanket AI Coverage Scope Means

Blanket additional insured coverage scope defines the categories of liability for which the additional insured receives protection under the named insured's policy. Understanding the scope is not optional. It determines whether a certificate holder is actually protected when a claim occurs.

The scope of blanket AI coverage varies based on which endorsement form is on the policy. CG 20 33, CG 20 37, CG 20 10, and CG 20 26 each carry different scope limitations. A broker who does not know which form is on the policy cannot accurately tell a client whether their certificate covers the required risk.

What Blanket AI Covers

Bodily Injury and Property Damage from the Named Insured's Operations

The core coverage under any blanket AI endorsement is bodily injury and property damage liability that arises out of the named insured's operations or work. The AI gets protection when a third party brings a claim related to the named insured's activities.

Example: a sub's employee drops a tool and injures a visitor to a job site. The project owner, named as an AI under the sub's blanket AI endorsement, gets tendered defense coverage because the injury arose from the sub's operations.

Defense Costs

Defense costs are included within the named insured's policy limits under standard ISO GL forms. When a claim triggers the AI endorsement, the carrier defends both the named insured and the AI. Defense costs erode the per-occurrence limit available to everyone sharing the policy.

This is important. Defense in complex construction claims can run $200,000 or more before trial. An AI expecting unlimited defense coverage will be surprised to find their protection is capped at the named insured's remaining per-occurrence limit.

Personal and Advertising Injury in Some Forms

Some blanket AI endorsement versions extend coverage to personal and advertising injury liability. The applicability depends on the edition year of the endorsement and any carrier modifications. Agents must review the specific endorsement form on the policy, not assume personal and advertising injury coverage is included.

Ongoing Operations (CG 20 33) or Completed Operations (CG 20 37)

The scope is also defined by which phase of operations is covered. CG 20 33 covers liability arising during active, ongoing work. CG 20 37 covers liability arising after the work is complete. Contracts must be reviewed to determine which phase or phases are required.

What Blanket AI Does NOT Cover

These exclusions are the source of most AI-related coverage disputes.

The AI's Own Independent Negligence

This is the most critical limitation. Blanket AI endorsements cover liability arising from the named insured's operations. They do not cover the AI's separate, independent acts of negligence.

If a GC is named as an AI on a sub's policy but the GC's own project management decision causes an injury, the sub's blanket AI endorsement does not cover that claim. The injury did not arise from the sub's operations; it arose from the GC's independent decision.

This exclusion is non-negotiable on standard ISO forms. Some contracts demand that AI coverage extend to the AI's sole negligence. No standard ISO endorsement provides this. When a contract makes this demand, it is creating a gap that the market cannot fill with standard forms.

Products-Completed Operations (Without CG 20 37)

If only CG 20 33 is on the policy, completed operations are not covered. A defective installation discovered after the project is finished is a completed operations claim. Without CG 20 37, neither the named insured nor the AI has AI endorsement coverage for that claim.

Coverage Beyond the Named Insured's Policy Limits

The AI does not receive their own separate policy limits. The AI shares the named insured's per-occurrence and aggregate limits alongside the named insured and all other AIs on the policy. A named insured with a $1M per-occurrence limit who has 10 active AI parties provides each of those parties with access to the same $1M limit, not $1M each.

This limit-sharing structure becomes significant when large projects involve multiple AI parties and significant claims. Agents must disclose this to clients when placing coverage and advise them that the AI's protection is constrained by the named insured's limits.

Claims Arising Before the Policy Period

Standard occurrence-based GL covers occurrences during the policy period. Prior work is not covered under a current policy. An AI endorsement on a 2026 policy does not provide coverage for work the named insured performed in 2024.

Contractual Liability Extensions Beyond Policy Scope

Some contracts demand that the AI receive coverage at least as broad as what the named insured's policy provides for itself. Standard ISO AI endorsements do not extend the full scope of the named insured's coverage to the AI. The AI's coverage is limited to the specific language of the AI endorsement, not the entire policy.

The "Arising Out of Your Work" Limitation in Practice

The "arising out of your operations" (or "arising out of your work") language defines the outer boundary of blanket AI coverage. It means the claim must have a causal connection to the named insured's activities.

Case Study: When the Limitation Works as Expected

A commercial cleaning contractor carried GL with CG 20 33 blanket AI. Their client, a property management company, was named as an AI. A building tenant slipped and fell near an area the cleaning crew had just mopped. The tenant sued both the cleaning contractor and the property management company.

The property management company tendered defense to the cleaning contractor's insurer under the CG 20 33. The carrier accepted: the slip arose from the cleaning contractor's ongoing operations, the written service agreement required AI status, and the property management company was a qualifying AI party. The carrier defended both the contractor and the property manager.

The "arising out of your work" test was satisfied because the slip had a direct causal connection to the cleaning crew's activities.

Case Study: When the Limitation Excludes a Claim

The same cleaning contractor and property management company were involved in a second situation. The property management company received a demand letter from a former tenant claiming the property manager failed to disclose a known mold problem during lease negotiations. This was a pure negligence claim against the property manager for its own independent decision not to disclose.

The property manager tendered to the cleaning contractor's insurer under the CG 20 33. The carrier denied the tender. The mold disclosure failure had no connection to the cleaning contractor's operations. The exclusion of the AI's own independent negligence applied directly.

Scope by Endorsement Form: Full Comparison

The combination of CG 20 33 and CG 20 37 covers both phases but still does not cover the AI's own independent negligence or provide separate limits. That limitation is inherent to all standard ISO AI forms.

The Contract vs. Policy Gap: The Leading Cause of AI Disputes

IIABA 2025 data shows that approximately 25% of AI-related coverage disputes involve a contract demanding coverage the endorsement does not actually provide. These gaps fall into three categories.

Gap 1: Completed operations required, only ongoing ops on the policy. The contract says "ongoing and completed operations" but the agent only placed CG 20 33. The completed operations AI claim is denied.

Gap 2: Sole negligence coverage demanded. The contract says "including the AI's sole negligence." No standard ISO form provides this. The agent issued the certificate anyway. A claim arises from the AI's own negligence. The tender is denied.

Gap 3: Separate limits demanded. The contract says the AI must have "its own $2M per-occurrence limit." Standard ISO AI forms share the named insured's limits. The carrier cannot provide separate limits. The certificate was issued without disclosing the limit-sharing structure.

Each of these gaps creates E&O exposure for the producing agent if the client was not informed that the coverage falls short of the contract requirement.

How Agents Close the Coverage Gap

The process has three steps.

Step 1: Read the contract AI language before placement. Do not wait until a certificate request arrives. Ask for the client's standard subcontract or service agreement template during the application process. Identify whether it requires ongoing ops, completed ops, or both. Identify whether it demands coverage for the AI's sole negligence or separate limits.

Step 2: Confirm the endorsement matches the requirement. Place the endorsement forms that satisfy the contract. If the contract requires completed operations AI, place both CG 20 33 and CG 20 37. If the contract demands sole negligence coverage or separate limits, advise the client in writing that the standard market cannot satisfy those demands.

Step 3: Document the gap in the file. When a contract demands coverage the market will not provide, write a coverage disclosure letter to the client explaining what the ISO endorsement does and does not cover. Document that the client received and acknowledged the letter. This documentation becomes the agency's defense if an E&O claim is later brought.

Policy Limit Sharing: What to Tell Clients

Every client with an active AI endorsement needs to understand the limit-sharing structure. Set the expectation at inception.

The explanation should be direct: "Your $1M per-occurrence limit is shared among you and all parties who hold AI status under your policy. If a large claim hits, the limits available to all of you are depleted from that single $1M. Your AI parties do not get their own separate limits."

For accounts with many active AI parties and significant project values, advise the client to consider higher GL limits. A contractor running $5M in annual project revenue with a $1M per-occurrence limit and 10 active AI parties has a meaningful limit adequacy exposure.

Frequently Asked Questions

Does blanket additional insured cover the AI's own negligence?

No. Standard ISO blanket AI endorsements cover liability arising out of the named insured's operations. They do not cover the additional insured's own independent acts of negligence. This limitation appears in all standard ISO AI forms. Contracts that demand AI coverage for the AI's sole negligence cannot be satisfied by standard market forms. Agents who encounter this contract demand must advise the client in writing that the coverage gap exists.

What is the coverage scope difference between CG 20 33 and CG 20 10?

CG 20 33 is a blanket form that automatically covers any party required by a written construction agreement, without naming each party individually. CG 20 10 is typically used as a scheduled form naming specific AI parties for ongoing operations. Both exclude completed operations and the AI's own negligence. CG 20 33 is more efficient for accounts with multiple rotating AI parties; CG 20 10 is used when a carrier requires specific approval of each AI party.

Do additional insureds get their own separate policy limits under blanket AI?

No. Additional insureds share the named insured's per-occurrence and aggregate limits. There is no separate limit for AI parties under any standard ISO AI endorsement form. A $1M per-occurrence policy provides $1M per occurrence shared among the named insured and all AIs. Agents must disclose this limit-sharing structure to clients at policy inception, particularly for accounts with many active AI parties or high project values.

Can a blanket AI endorsement cover completed operations?

Yes, but only with the CG 20 37 endorsement. CG 20 33 covers ongoing operations only; it does not extend to completed operations. CG 20 37 covers completed operations only. Contracts requiring AI coverage for both phases need both endorsements. Agents placing coverage for construction accounts should review whether the client's standard subcontracts require completed operations AI and add CG 20 37 accordingly.

What is the most common scope gap between contract AI requirements and blanket AI endorsements?

Per IIABA 2025 data, the most common gap is a contract requiring AI coverage for completed operations when only CG 20 33 (ongoing operations) is on the policy. The second most common gap is a contract demanding AI coverage for the AI's sole negligence, which no standard ISO form provides. The third is a contract demanding separate AI limits, which are not available under standard ISO forms. Each of these gaps creates E&O exposure for the agent if the client was not informed.

How should a broker explain blanket AI coverage scope limitations to a client?

Use plain language and focus on the two most common surprises. First: "The AI endorsement on your policy covers claims that arise from your work. It does not cover your clients' own separate mistakes." Second: "Your policy limits are shared. If a big claim comes in, the limits cover you and your AI parties combined, not separately." Provide this explanation in writing at inception and document the client's acknowledgment. When a contract demands broader coverage, write a gap letter explaining what the market provides and what it does not.

BrokerageAudit's COI Manager tracks the specific AI endorsements and coverage scope for every policy so you can quickly verify whether a certificate can legitimately reflect the required coverage. See how it works →

Related terms: Primary And Noncontributory, Prior Acts Coverage, Blanket Additional Insured

Related posts: #161, #165

Written by Javier Sanz, Founder of BrokerageAudit. Last updated April 2026.