Blanket Additional Insured Endorsement
Written by Justin Goodman, CIC, CRIS, CCIP, CEO and Co-Founder, Total CSR
Published: August 20, 2026 · Last reviewed: August 20, 2026
In plain language: A Blanket Additional Insured Endorsement adds insurance coverage automatically for anyone the policyholder has agreed in writing to protect, like a general contractor or a landlord, without the agency issuing a separate endorsement for each construction project or lease.
Technical definition: A Blanket Additional Insured Endorsement modifies a general liability insurance policy's "Who Is An Insured" section to extend additional insured status to any person or organization the named insured is required to add by a written contract or contractual agreement, subject to the endorsement's scope of coverage, timing, and limitation provisions.
Blanket Additional Insured Endorsement at a Glance
| Attribute | Detail |
|---|---|
| Also known as | Blanket AI Endorsement, Automatic Additional Insured Endorsement |
| Category | Liability policy endorsement |
| Lines of business | Commercial General Liability, Commercial Umbrella/Excess Liability |
| Industries most affected | Construction industry, real estate/property management, manufacturing, trucking, equipment rental |
| Related forms or endorsements | CG 20 33, CG 20 38, CG 20 10, CG 20 37 |
| Who bears the risk | Named insured's insurance company, subject to endorsement scope and contract wording |
| Common solution | Blanket endorsement tied to "written contract" trigger instead of scheduled endorsements |
| Also interacts with | Certificate of insurance issuance, primary and noncontributory wording, waiver of subrogation |
Key Takeaways
- A Blanket Additional Insured Endorsement automatically grants additional insured coverage to any party the named insured has agreed by written contract to add, without a separate endorsement per construction project or rental agreements.
- Agencies rely on blanket endorsements to keep certificates of insurance accurate on fast-moving construction and lease-driven accounts where new certificate holders are added weekly.
- The most common misunderstanding is assuming blanket wording covers completed operations or ongoing operations equally; many blanket insurance forms only extend during ongoing operations unless a completed operations blanket endorsement is also attached.
- Agencies should always confirm the underlying written contract exists and is signed before the loss date, because blanket additional insured status typically will not apply without meeting these contract requirements.
What Is a Blanket Additional Insured Endorsement in Insurance?
A Blanket Additional Insured Endorsement is a CGL policy modification that extends additional insured status automatically to any person or organization the named insured is required to add under a written contract, without listing that party by name on a scheduled endorsement. Insurance companies created blanket forms to solve a volume problem: general contractors, property managers, and manufacturers often sign dozens of construction contracts a month, each requiring the same additional insured obligation, and issuing a separate scheduled endorsement for every one is operationally unworkable.
The provision exists because certificate holders, most often owners, general contractors, and landlords, want contractual proof that they share in the named insured's liability coverage before work begins or a lease starts. Rather than amending the insurance policy contract-by-contract, the blanket endorsement shifts the trigger from "who is scheduled" to "who does the named insured owe this obligation to under a signed written agreement." The insurance provider is protecting against gaps that arise when paperwork lags behind actual business activity.
Consider a drywall subcontractor who signs a new subcontract with a general contractor on a Tuesday and starts work on the jobsite the following Monday. With a blanket additional insured endorsement in place, the general contractor has additional insured status from the moment the written subcontract exists and requires it, without the agency needing to process anything. Without the blanket endorsement, the subcontractor's CSR would need to issue and file a scheduled CG 20 10-style endorsement naming that specific general contractor before insurance coverage would attach to that party.
Blanket endorsements typically reference the ISO endorsements CG 20 33 (ongoing operations) and CG 20 38 (ongoing and completed operations), which extend automatic status "when required in a construction agreement" or "written contract or agreement." The exact scope of coverage, including whether completed operations are included, depends entirely on which specific edition is attached to the insurance policy.
How Does a Blanket Additional Insured Endorsement Work?
- The contract is signed. The named insured enters a written contractual agreement, such as a subcontract, lease, equipment rental agreement, or purchase order, that obligates it to name the other party as an additional insured on its general liability insurance policy.
- The endorsement activates automatically. Because the CGL policy carries a blanket additional insured endorsement, the other party's status attaches without the agency filing a scheduled endorsement naming them individually.
- The certificate is requested. The additional insured party, or its risk manager, requests a certificate of insurance as proof of insurance, and the agency issues it referencing the blanket endorsement and the underlying contract.
- The loss occurs. A third party suffers bodily injury or property damage in connection with the named insured's operations, and the additional insured is named in the resulting claim or lawsuit.
- The coverage is confirmed. The insurance company verifies a qualifying written contract existed before the loss and that the endorsement's scope, ongoing operations, completed operations, or both, covers the type of loss alleged, then extends duty to defend and indemnity to the additional insured.
Real Claim Examples Involving Blanket Additional Insured Endorsement
Scaffolding collapse on a mid-rise apartment project
A general contractor building a mid-rise apartment complex was named in a lawsuit after scaffolding erected by its framing subcontractor collapsed, causing bodily injury to a passerby. The subcontractor's CGL policy carried a CG 20 33 blanket additional insured endorsement, and the signed construction contracts required the general contractor to be added as an additional insured. Because the written subcontract predated the incident and the loss occurred during ongoing operations on the construction project, the subcontractor's insurance company accepted the tender and defended the general contractor without a separately issued endorsement ever existing.
Slip and fall at a retail center after project completion
A property management company was sued after a customer slipped on uneven pavement outside a retail unit that had been repaved by a paving contractor eight months earlier. The paving contractor's insurance policy carried only a CG 20 33 ongoing operations blanket endorsement, not the CG 20 38 version that also covers completed operations. The property manager's tender was denied because the property damage loss occurred after the paving work was completed and accepted, illustrating why blanket endorsement scope of coverage matters as much as its existence.
Verbal agreement disputed after a warehouse fire
A logistics company claimed additional insured status on a trucking firm's policy after a warehouse fire damaged goods in transit, but no signed contractual agreement existed at the time of loss, only an email exchange referencing future terms. The trucking firm's blanket additional insured endorsement required a "written contract or agreement" in place, and the insurance provider denied additional insured coverage because the email did not constitute an executed agreement under the policy language terms.
Blanket Additional Insured Endorsement vs. Scheduled Additional Insured Endorsement: What Is the Difference?
A Blanket Additional Insured Endorsement and a Scheduled Additional Insured Endorsement both extend liability coverage to a third party, but they differ in how that party is identified and how the insurance protection attaches to the policy.
| Comparison area | Blanket Additional Insured Endorsement | Scheduled Additional Insured Endorsement |
|---|---|---|
| Primary use case | High-volume contracting or leasing relationships with frequent new parties | Single, known additional insured named at policy inception or by mid-term change |
| Coverage / concept type | Automatic status tied to a written contract requirement | Named-party status added by specific endorsement |
| Typical exclusions | Verbal agreements, unsigned contracts, parties not covered by contract language | Any party not specifically listed on the schedule |
| Who is most affected by errors | Contractors and subs juggling many simultaneous jobsite agreements | Agencies managing static, long-term relationships like a single landlord |
| Common mistakes | Assuming blanket wording covers completed operations when it does not | Forgetting to add a new additional insured after insurance requirements change |
What Are the Most Common Mistakes With Blanket Additional Insured Endorsements?
- Assuming the blanket endorsement covers completed operations. Many blanket endorsements, including CG 20 33, apply only to ongoing operations, so claims arising after construction project completion may be denied unless the CG 20 38 completed operations version is also attached.
- Issuing certificates without confirming a written contract exists. Certificates that reference a blanket additional insured endorsement create a false sense of security if no signed contractual agreement requiring that status was in place before the loss, a common E&O trap for agencies.
- Treating the certificate of insurance as proof of coverage. A certificate is not a contract and does not by itself grant additional insured status; only the endorsement and the underlying written agreement control, despite certificate holders expecting it to serve as proof of insurance.
- Overlooking the umbrella policy. A blanket additional insured endorsement on the primary CGL does not automatically follow through to the umbrella or excess insurance policy unless that policy separately incorporates the underlying schedule or contains its own blanket language with matching policy limits.
- Failing to verify the endorsement edition date. ISO revised additional insured forms multiple times to narrow the scope of coverage, and an older edition may extend broader insurance protection than the one currently attached to a renewal.
- Confusing blanket additional insured status with primary and noncontributory wording. Blanket status determines who is covered; primary and noncontributory wording determines how that insurance coverage responds relative to the additional insured's own policy, and agencies sometimes assume one implies the other.
How to Explain a Blanket Additional Insured Endorsement to a Client
Explaining Blanket Additional Insured Endorsement to a personal lines client
Blanket additional insured endorsements almost never apply to personal lines policies, so this conversation rarely comes up for homeowners or auto clients. If a personal lines client is asked to be named as an additional insured, such as through a landlord's requirement on a renter's policy, explain that this is a business insurance concept and direct them to confirm with their landlord what specific insurance requirements are actually needed.
Explaining Blanket Additional Insured Endorsement to a small business owner
Tell the client that this endorsement means anyone they are contractually required to add as an additional insured gets that insurance protection automatically, as long as the contractual agreement is in writing and signed before work starts. Emphasize that verbal promises or handshake deals will not trigger coverage, so every subcontract, rental agreements, or lease needs a signature before the first day on the job. Remind them that completed operations coverage may need to be added separately if their construction contracts require ongoing protection after a construction project wraps up.
Explaining Blanket Additional Insured Endorsement to a CFO or risk manager
Walk through the specific endorsement edition attached to the insurance policy, whether it is CG 20 33 or CG 20 38, since that single distinction determines whether completed operations claims are covered. Confirm whether the umbrella or excess policy follows form to the same blanket language, since gaps between primary and excess additional insured treatment are a frequent source of coverage disputes. Offer to audit a sample of their standard contract templates against the endorsement's "written contract" trigger language to confirm the contractual obligations they are promising vendors and clients are actually being met. Also review how this interacts with other commercial coverages like workers compensation, commercial auto insurance, and any business owners policy they maintain.
Frequently Asked Questions About Blanket Additional Insured Endorsements
Does a Blanket Additional Insured Endorsement cover completed operations?
It depends entirely on which endorsement edition is attached to the insurance policy. CG 20 33 typically covers only ongoing operations, while CG 20 38 extends to both ongoing and completed operations, so agencies must verify the exact form number rather than assume broader scope of coverage exists.
Is a certificate of insurance enough to prove additional insured status?
A certificate of insurance is not a contract and does not by itself grant insurance coverage; it is only evidence that an insurance policy exists at the time it was issued. Actual additional insured status depends on the policy language and the underlying written contract, which is why certificates typically carry a disclaimer stating they confer no rights to the certificate holder.
Does a Blanket Additional Insured Endorsement require a written contract?
Nearly all blanket additional insured endorsements require a written contract or contractual agreement that specifically obligates the named insured to add the other party as an additional insured. A verbal agreement or an unsigned draft generally will not satisfy this requirement, which has led to coverage denials in real claims.
Can a Blanket Additional Insured Endorsement be added to an umbrella policy?
Yes, but it does not happen automatically just because the primary CGL carries one. The umbrella or excess insurance policy needs its own blanket additional insured provision, or language that follows form to the underlying schedule, and agencies should confirm this explicitly rather than assume it transfers. Policy limits and policy term should also align between primary and excess layers.
What happens if the contract requiring additional insured status is signed after the loss?
Insurance coverage will typically be denied because most blanket endorsements require the written contract to be in effect before the date of the occurrence. This is one of the most common reasons additional insured tenders fail, particularly on fast-moving construction projects where paperwork lags behind fieldwork during the bidding process.
How is a Blanket Additional Insured Endorsement different from naming someone on the declarations page?
Naming a party on the declarations page or through a scheduled endorsement identifies a specific additional insured by name at policy inception or by mid-term change. A blanket endorsement instead creates a standing rule that automatically extends status to any party who meets the contract-based trigger, without the agency having to process anything for each new relationship or issue a notice of cancellation when relationships end.
Related Insurance Terms
- Additional Insured: A person or organization, other than the named insured, granted liability coverage under someone else's insurance policy, most often required through a written contract such as a lease or subcontract.
- Certificate of Insurance: A document summarizing an insurance policy's coverage and policy limits at a point in time, often requested by additional insureds as proof of insurance but carrying no contractual weight of its own.
- Primary and Noncontributory Wording: An endorsement provision stating that the named insured's insurance policy pays first and does not share costs with the additional insured's own policy, frequently required alongside blanket additional insured status.
- Waiver of Subrogation: A provision preventing an insurance company from pursuing recovery against a specified party after paying a claim, commonly required in the same contracts that trigger blanket additional insured status.
- Named Insured: The person or business specifically identified on the policy declarations as the primary party insured, distinct from any additional insured added by endorsement.
- Ongoing Operations Coverage: Liability coverage that applies while work is actively in progress, a scope limitation relevant to whether a blanket additional insured endorsement extends to claims after construction project completion.
- Workers Compensation: Insurance coverage that provides medical payments and wage replacement benefits to employees injured on the job, often required alongside general liability insurance in construction contracts.
- Commercial Auto Insurance: Coverage for vehicles used in business operations, frequently required in addition to general liability when contractors or equipment rental companies operate vehicles on job sites.
- Professional Liability: Insurance protection for claims arising from professional errors or omissions, sometimes called errors and omissions insurance, which may be required alongside general liability for design-build contractors.
- Cyber Insurance: Coverage for data breaches and cyber incidents, increasingly required in contracts alongside traditional liability coverages as businesses handle more digital information.
- Manuscript Endorsements: Custom-drafted policy modifications created for specific situations when standard ISO endorsements do not meet unique contractual obligations or insurance requirements.
Sources and References
- Insurance Services Office (ISO) - form referenced via IRMI. Additional Insured - Owners, Lessees or Contractors - Automatic Status When Required in Construction Agreement With You (CG 20 33).
- International Risk Management Institute (IRMI). Additional Insured.
About the Author
Justin Goodman, CIC, CCIP, CISC, CLCS, CRIS, PCIA, QCLS, MFHR
CEO and Co-Founder, Total CSR, Inc.
Justin Goodman is a third-generation insurance broker with over two decades in agency operations. He has trained more than 50,000 CSRs, account managers, and producers in commercial and personal lines coverage, from workers compensation to construction risk. He was named 2024 Insurance Journal Agent of the Year and one of the nation's top five construction insurance experts by Risk & Insurance. He is the author of Retain, which applies cognitive science research on memory and knowledge transfer to insurance training, and speaks nationally on how agencies build durable technical expertise in their teams.