· Updated June 6, 2026

What Is an Additional Insured? Complete Guide | COI File

What additional insured means on a certificate of insurance, the critical difference between certificate holder and additional insured, endorsement types, and how to verify you are actually covered.

If you manage commercial properties or oversee construction projects, you've heard the term "additional insured" hundreds of times. You know you need it on every vendor's COI. But what does it actually mean -- and more importantly -- are you sure you're getting the right coverage?

This guide explains what additional insured status means, how it differs from being a certificate holder (a mistake that costs thousands), the endorsement types that matter, and how to verify you're truly protected.

What Is an Additional Insured?

An additional insured is a person or entity that is added to another party's insurance policy and receives coverage under that policy. In the COI world, this typically means a property manager, general contractor, or project owner is added to a vendor's or subcontractor's general liability policy.

Here's the key concept: when a vendor performs work at your property, their operations create risk. If their employee damages your building or injures a tenant, the vendor's general liability policy should cover the loss. But if you're not listed as additional insured on that policy, you may have no direct right to make a claim. You'd have to sue the vendor and prove negligence -- a slow, expensive process with no guaranteed outcome.

Being named as additional insured gives you direct access to the vendor's insurance policy. If a claim arises from the vendor's work, you can file directly against their policy. The vendor's insurer defends you and pays covered claims -- just as they would for the vendor themselves.

Additional insured coverage is not automatic. It requires the vendor's insurance agent to issue an endorsement -- a formal amendment to the policy that adds you as a covered party. Simply being named in the certificate holder box on a COI does not make you an additional insured.

Certificate Holder vs. Additional Insured: The Critical Difference

This is the single most misunderstood concept in insurance compliance -- and the most expensive. Here's the difference:

Feature Certificate Holder Additional Insured
Purpose Receives proof that insurance exists Receives actual coverage under the policy
Can file a claim? No Yes -- directly against the vendor's policy
Insurer must defend? No Yes -- insurer provides legal defense
Receives cancellation notice? Yes -- 30 days notice if policy is cancelled Yes -- depending on state law and policy terms
Requires endorsement? No (listed in certificate holder box on ACORD 25) Yes -- formal endorsement (CG 20 10, CG 20 37, etc.)
Common mistake Assuming this provides coverage (it does not) Not verifying the correct endorsement was used

Many property managers and contractors file COIs believing they're covered because their name appears on the certificate. But if their name only appears in the certificate holder box -- not backed by an additional insured endorsement -- they have zero protection. This is the most common and most dangerous compliance mistake.

Types of Additional Insured Endorsements

Not all additional insured endorsements are equal. The specific form the agent uses determines the scope of your coverage. Here are the most important ones:

CG 20 10 vs. CG 20 37

CG 20 10 -- Additional Insured -- Owners, Lessees or Contractors (Scheduled) is the older, more limited endorsement. It covers the additional insured only for liability arising from the named insured's ongoing operations -- meaning the work being performed right now. Once the vendor finishes the job, coverage under CG 20 10 typically ends.

CG 20 37 -- Additional Insured -- Owners, Lessees or Contractors (Completed Operations) is the newer, broader endorsement. It extends additional insured coverage to include completed operations -- meaning you're still covered after the vendor finishes work and leaves the site. This is critical because construction defects, water damage from faulty plumbing, and electrical fires often manifest months or years after project completion.

Most property managers and general contractors should require CG 20 37 or its equivalent. CG 20 10 leaves a significant coverage gap for completed operations claims.

Scheduled vs. Blanket Additional Insured

Scheduled additional insured means the endorsement specifically names each additional insured entity. For example: "ABC Property Management LLC is added as additional insured per CG 20 10." If the vendor works with a new property manager next month, the agent must issue another endorsement. This works fine for small relationships but becomes administrative overhead for contractors working with dozens of clients.

Blanket additional insured means the policy automatically extends additional insured status to any entity that the named insured is contractually required to add as additional insured. The endorsement typically reads: "Any person or organization that you are required to add as an additional insured under a written contract or agreement." This is more convenient for large contractors but still requires a written contract specifying the requirement.

Why Being Additional Insured Matters

The consequences of not being named as additional insured are severe:

  • No direct claim rights. If a vendor's employee falls off a ladder and sues you, the vendor's general liability policy won't defend you unless you're additional insured. You bear your own defense costs and potential settlement.
  • Your insurance pays first. Without additional insured status, your own general liability or property policy becomes the primary coverage for claims arising from the vendor's work. Your premiums increase. Your loss history worsens.
  • Contract breach. Most commercial leases, construction contracts, and property management agreements require that vendors add the property owner or GC as additional insured. Failing to enforce this is a breach of your own obligations.
  • Real-world example: A roofing contractor's employee accidentally starts a fire that causes $500,000 in damage to a shopping center. The property manager was listed as certificate holder only -- not additional insured. The roofer's insurer denied the property manager's claim. The property manager's own policy paid the claim after a $25,000 deductible, and their premium increased 30% at renewal.
  • Another example: An HVAC contractor installs a unit incorrectly. Six months later, water damage from the faulty installation ruins $80,000 in tenant inventory. Because the property owner was additional insured under a CG 20 37 completed operations endorsement, the HVAC contractor's insurer covered the loss. Without completed operations coverage, the property owner would have been on their own.

How to Verify You Are Actually an Additional Insured

Checking the COI alone isn't enough. Follow these steps to verify your additional insured status:

  1. Check the COI's Description of Operations section. Look for language explicitly stating "[Your Entity] is added as additional insured." The exact entity name must match your legal name.
  2. Confirm the endorsement form. The COI should reference the specific endorsement form used (e.g., CG 20 10, CG 20 37). If no form number is listed, the additional insured status is questionable.
  3. Request a copy of the endorsement. Ask the vendor's agent to provide the actual additional insured endorsement page from the policy. This is the definitive proof. Many organizations make this a standard requirement in their vendor contracts.
  4. Check for completed operations coverage. If your contract requires CG 20 37 or equivalent, verify the endorsement references completed operations -- not just ongoing operations.
  5. Verify the policy is active. An additional insured endorsement is worthless if the underlying policy is expired or cancelled. Check the effective and expiration dates first.
  6. Keep records. Save the COI, the endorsement, and all correspondence with the vendor and agent. If a claim occurs, you'll need to prove your additional insured status to the insurer.

Contract Language for Additional Insured Requirements

Your contracts need clear, enforceable additional insured language. Vague terms like "vendor shall provide insurance" aren't enough. Here's what effective contract language includes:

  • Specific endorsement: "Vendor shall name [Entity] as additional insured on the General Liability policy using ISO form CG 20 37 or equivalent, including completed operations coverage."
  • Primary and non-contributory: "The vendor's insurance shall be primary and non-contributory with respect to any insurance maintained by [Entity]."
  • Waiver of subrogation: "Vendor's insurer shall waive all rights of subrogation against [Entity]."
  • Proof requirement: "Vendor shall provide a certificate of insurance and a copy of the additional insured endorsement at least 10 days before commencing work."
  • Coverage duration: "Additional insured coverage shall remain in effect for the duration of the work and for [X] years following completion for completed operations claims."

Standard industry contracts (AIA, ConsensusDocs) typically include this language, but many smaller vendors and property managers use informal agreements that omit these critical provisions. Review your contracts. If the additional insured language is missing or vague, fix it before the next vendor starts work.

Frequently Asked Questions

Additional insured means that a person or entity (usually the property manager, general contractor, or project owner) is added to a vendor's insurance policy and receives coverage under that policy for liability arising from the vendor's work. The additional insured is protected against claims caused by the named insured's operations -- for example, if a subcontractor damages a building, the property manager listed as additional insured is covered under the subcontractor's general liability policy.
No. A certificate holder simply receives a copy of the COI as proof that insurance exists. They have no coverage under the policy. An additional insured is actually covered by the policy and can file a claim if the named insured's operations cause damage or injury. This is a critical distinction -- many organizations believe they're protected when they're only listed as certificate holder, which provides zero coverage.
On an ACORD 25 form, look at the Description of Operations section (usually near the bottom). If you're additional insured, there will be language like "[Your Entity Name] is added as additional insured on the General Liability policy per endorsement CG 20 10" or similar. The additional insured box on the COI is not sufficient by itself -- you need an actual endorsement issued by the insurer. Always request a copy of the endorsement if you're unsure.
CG 20 10 provides additional insured coverage for ongoing operations only -- meaning you're covered while the vendor is actively performing work. CG 20 37 extends coverage to include completed operations -- meaning you're also covered after the work is finished, which is when many construction defect claims arise. CG 20 37 is the preferred endorsement for most property managers and contractors because it provides ongoing + completed operations coverage. CG 20 10 is the older, less comprehensive form.
A blanket additional insured endorsement automatically extends additional insured status to any entity that the named insured is contractually required to add as additional insured. Instead of scheduling each additional insured individually (which requires an endorsement amendment for every new entity), the blanket endorsement covers anyone named in a written contract or agreement. This is common with larger contractors who work with many different property managers and GCs.
If you are not listed as additional insured, you have no direct coverage under the vendor's policy. You would need to sue the vendor and prove their negligence to recover damages -- an expensive and uncertain process. Your own insurance may cover the loss, but you'll pay the deductible and your premiums may increase. In some cases, your insurer may deny the claim entirely if they determine the loss should have been covered by the vendor. Being additional insured prevents all of this by giving you direct access to the vendor's policy.

Sources & References

  • International Risk Management Institute (IRMI) -- Definitive resource on additional insured endorsements and their legal implications. irmi.com
  • Insurance Services Office (ISO) -- The organization that creates standard endorsement forms including CG 20 10 and CG 20 37. verisk.com
  • ACORD -- Official standards body for the ACORD 25 certificate of insurance form. acord.org
  • Nationwide -- Additional Insured Guide -- Practical overview of additional insured endorsements. nationwide.com
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Firdaosh Bano

COI Compliance Specialist

Firdaosh Bano is a COI compliance specialist and the founder of COI File. She spent 6 years managing vendor compliance for commercial properties - tracking 2,000+ COIs across 150+ properties in spreadsheets before building the tool she wished she'd had. She writes about certificate of insurance compliance, vendor risk management, and making insurance tracking less painful for small teams.

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