Additional Insured in Insurance: Complete Guide for the United States
📄 AIStandard Abbreviation in Insurance
CG 20 10Most-Used ISO Endorsement Form
ACORD 25Standard COI Form Used
CGLPrimary Policy Type Involved
An additional insured (AI) is a person or entity — other than the named insured — who is granted coverage under someone else’s insurance policy at the request of the named insured. Common examples include landlords added to a tenant’s general liability policy, and general contractors added to a subcontractor’s policy. The additional insured is protected against third-party claims arising from the named insured’s operations or use of the premises.
The additional insured concept is one of the most fundamental and widely used in commercial insurance in the United States. Nearly every commercial lease, construction contract, vendor agreement, and franchise agreement in America includes a requirement that one party add the other as an additional insured. Understanding how additional insured status works — what it covers, what it does not cover, and how it is properly documented — is essential for any business operating in the U.S.
Additional insured status is granted through a policy endorsement — a written amendment to the base policy. The most widely used endorsements are developed by the Insurance Services Office (ISO), whose standardized Commercial General Liability (CGL) forms (CG 20 10, CG 20 37, and others) define the scope of additional insured coverage. This article explains the complete additional insured framework as it applies in the United States.
Insurance Glossary Definition — InsureBlogging.com
Additional Insured (AI) — A person or entity covered under the policy at the request of the named insured, such as a landlord or general contractor.
Abbreviation: AI | Type: Concept | Category: General Terms
Core Purpose: Extend liability protection to a third party with a legitimate interest in the named insured’s operations | Source: ISO; NAIC; IRMI; ACORD
| Term | Definition |
|---|---|
| Additional Insured (AI) | Person or entity granted coverage under another party’s insurance policy, through an endorsement, at the named insured’s request |
| Named Insured | The primary policyholder — the person or business named on the declarations page who purchased the policy |
| Endorsement | Written amendment to an insurance policy that adds, deletes, or modifies policy terms; the legal mechanism for adding an additional insured |
| ISO | Insurance Services Office — drafts and maintains standardized insurance policy forms and endorsements used across the U.S. industry |
| CGL Policy | Commercial General Liability — the most common policy type for additional insured endorsements; covers bodily injury and property damage |
| Certificate of Insurance (COI) | Summary document evidencing insurance coverage; typically used to confirm additional insured status; not a substitute for the endorsement |
| Certificate Holder | Entity listed on a COI to receive a copy; does NOT automatically receive additional insured coverage — additional insured status requires an endorsement |
| Additional Interest | Different from additional insured; typically refers to a lender or lienholder with a financial interest in property (e.g., mortgagee) — not a liability coverage concept |
| Loss Payee | Party designated to receive property insurance claim payments (e.g., bank/lender on auto or property policy); distinct from additional insured status |
| Primary & Non-Contributory | Endorsement specifying that the named insured’s policy is primary and will not seek contribution from the additional insured’s own policy |
| Waiver of Subrogation | Provision preventing the insurer from recovering claim payments from the additional insured after paying a claim |
The additional insured mechanism follows a consistent process across commercial insurance transactions in the U.S.:
Contract Requires AI
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Named Insured Requests AI from Insurer
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Insurer Issues AI Endorsement
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COI Issued to AI
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AI Has Coverage Under Policy
Step-by-Step Process
- Contractual requirement: A contract (lease, construction agreement, vendor contract) requires one party to add the other as an additional insured on their liability policy.
- Named insured contacts insurer: The policyholder (named insured) requests the insurer to add the specified party as an additional insured via an endorsement.
- Endorsement issued: The insurer amends the policy with an additional insured endorsement (often a standardized ISO form). This is the legal addition — not the COI.
- Certificate of Insurance issued: The insurer or broker issues a Certificate of Insurance (ACORD Form 25) confirming the additional insured’s status for record-keeping.
- Coverage activates on claim: If a third party sues the additional insured for liability arising from the named insured’s operations, the named insured’s CGL policy responds to defend and indemnify the additional insured.
⚠️ COI Is NOT the Coverage: A Certificate of Insurance is evidence of insurance, not the insurance itself. Courts have repeatedly held that COI language cannot expand or contract the actual endorsement. If the endorsement was never issued — or has different terms than the COI states — the COI does not create additional insured coverage. Always verify the actual endorsement, not just the COI.
🏢 Landlord / Tenant
- Named Insured: Tenant (business lessee)
- Additional Insured: Landlord / property owner
- Why: Landlord exposed to liability for tenant’s operations on premises
- Example: Customer slips in tenant’s retail store; landlord is sued as property owner
- ISO Form: CG 20 11 (Managers / Lessors of Premises)
👷 General Contractor / Subcontractor
- Named Insured: Subcontractor
- Additional Insured: General Contractor (GC)
- Why: GC vicariously liable for sub’s work; contract requires sub to protect GC
- Example: Subcontractor’s employee injures a bystander; GC is sued
- ISO Forms: CG 20 10 (ongoing) + CG 20 37 (completed operations)
🏦 Lender / Mortgagee
- Named Insured: Borrower / property owner
- Additional Insured: Bank / lender (on liability policy)
- Why: Lender requires protection against liability arising from the financed property
- Note: Lenders more commonly appear as Loss Payee on property policies
- ISO Form: CG 20 28 (Loss of Use) or custom endorsement
🎯 Franchisor
- Named Insured: Franchisee (individual location owner)
- Additional Insured: Franchisor (brand owner)
- Why: Franchisor exposed to liability for franchisee’s operations under its brand
- Example: Customer injured at franchise location sues the parent brand
- ISO Form: CG 20 59 (Franchisors)
🏛️ Government / Public Entity
- Named Insured: Contractor / event organizer / vendor
- Additional Insured: City, county, state agency, school district
- Why: Government entity grants permits or right-of-way; requires liability protection
- Example: Road contractor adds city as AI for work on public streets
- Form: Custom government AI endorsement or CG 20 12
📋 Vendor / Supplier
- Named Insured: Vendor / product manufacturer
- Additional Insured: Retailer or distributor
- Why: Retailer exposed to product liability claims from vendor’s products sold in its store
- Example: Consumer injured by defective product sues both manufacturer and retailer
- ISO Form: CG 20 15 (Vendors)
The Insurance Services Office (ISO) maintains standardized CGL endorsement forms for adding additional insureds. These forms define the exact scope of coverage granted. Key forms include:
CG 20 10
Owners, Lessees or Contractors — Ongoing Operations
Most commonly required in construction; covers AI for liability from named insured’s ongoing (in-progress) work. Often paired with CG 20 37.
CG 20 37
Owners, Lessees or Contractors — Completed Operations
Covers AI for liability from named insured’s completed (finished) work. Required in construction for post-completion claims (e.g., structural defect found after project closes).
CG 20 11
Managers or Lessors of Premises
For landlord/tenant situations. Covers landlord (AI) for liability arising from the tenant’s (named insured’s) operations on the leased premises.
CG 20 15
Vendors
Adds a vendor (retailer/distributor) as AI for product liability claims arising from the named insured’s products distributed through the vendor’s channels.
CG 20 26
Designated Person or Organization
Broad, flexible form covering a specifically named person or organization as AI for any liability arising from the named insured’s operations. Often broader than activity-specific forms.
CG 20 33
Owners, Lessees or Contractors — Auto & Equipment
Used when the AI relationship involves equipment or vehicles; less common than CG 20 10/37 in standard construction contexts.
CG 20 38
Additional Insured — State or Governmental Agency
Specifically designed for government entity additional insureds, often required for public permits, right-of-way access, or government contracts.
CG 20 59
Additional Insured — Franchisors
Tailored for franchise relationships; covers the franchisor (AI) for liability arising from the franchisee’s (named insured’s) operations under the franchise agreement.
ℹ️ 2013 ISO Form Revisions: In 2013, ISO significantly revised its additional insured endorsement forms to limit coverage to liability “caused, in whole or in part, by” the named insured’s acts or omissions. This is narrower than earlier versions, which covered the additional insured for the named insured’s “operations.” Many insureds and additional insureds still negotiate for broader manuscript (custom-drafted) endorsements that restore wider coverage.
| Feature | Named Insured | Additional Insured | Certificate Holder |
|---|---|---|---|
| Who | Primary policyholder; first named on declarations page | Third party added by endorsement at named insured’s request | Entity listed on COI to receive a copy of the certificate |
| Coverage | Full policy coverage; all coverages, conditions, and terms apply | Limited coverage for liability from named insured’s operations (per endorsement) | No coverage — listing on COI does not create insurance rights |
| Policy Rights | Full: cancellation notice, full policy copy, claim filing rights | Limited: claim defense and indemnity; may receive cancellation notice per endorsement | May receive cancellation notice if stated on COI; no substantive rights |
| Premium Obligation | Pays the premium | Does not pay premium | Does not pay premium |
| Created By | Policy declarations page | Policy endorsement (ISO form or custom) | COI document only (no endorsement needed) |
| Own Negligence Covered? | Yes (within policy terms) | Generally NO — only for liability from named insured’s acts (post-2013 ISO forms) | N/A — no coverage |
| Common Example | ABC Contractors, LLC (buys CGL) | City of Chicago (added as AI on ABC’s CGL) | Bank of America (listed on COI for record) |
🚨 Certificate Holder ≠ Additional Insured: This is one of the most common insurance mistakes in the U.S. commercial market. Being listed as a certificate holder on an ACORD Form 25 does NOT make a party an additional insured. The certificate holder receives a copy of the COI — nothing more. Additional insured status requires a separate, written endorsement to the actual policy. Courts consistently reject claims by parties who were listed as certificate holders but not named in an AI endorsement.
✅ What Is Typically COVERED
- Defense costs for claims against the AI arising from named insured’s operations
- Indemnity for damages where named insured’s acts caused the claim (in whole or in part)
- Bodily injury and property damage claims by third parties
- Personal and advertising injury (if AI endorsement includes it)
- Vicarious liability: AI sued because of what named insured did
- Ongoing operations (CG 20 10) and completed operations (CG 20 37)
❌ What Is Typically EXCLUDED
- AI’s own independent negligence (post-2013 ISO forms)
- Claims not arising from named insured’s operations
- Professional liability / E&O (separate policy needed)
- Workers’ compensation claims (separate policy)
- Employer’s liability for AI’s own employees
- Claims covered under a separate policy maintained by the AI
- Claims arising after policy expiration (unless completed ops endorsement in force)
- Damage to AI’s own property
Coverage Limit Considerations
| Issue | Explanation |
|---|---|
| Limits Shared | The additional insured shares the named insured’s policy limits. A $1M per-occurrence limit is shared between all claimants and all insureds under that policy |
| No Separate Limit | Additional insureds do not receive a separate, dedicated limit — they access the same aggregate limits as the named insured |
| Aggregate Erosion | Claims paid for the named insured erode the aggregate; less may be available for additional insured claims later in the policy year |
| Umbrella / Excess | Many contracts require the additional insured to also be named on the umbrella/excess liability policy for coverage above the primary limit |
| Minimum Required Limits | Contracts typically specify minimum policy limits (e.g., $1M/$2M CGL) before AI status is acceptable; higher limits may be required for certain industries |
A Certificate of Insurance (COI) is the standard document used in commercial insurance to confirm that a policy exists and that a party has been added as an additional insured. In the U.S., COIs are almost universally issued on ACORD Form 25 (Certificate of Liability Insurance).
📋 What ACORD Form 25 Shows
| Insured (Named Insured) | Name and address of the policyholder (e.g., ABC Contractors, LLC) |
| Insurer(s) | Name and NAIC number of each insurance company |
| Policy Type & Number | CGL, Auto, Workers’ Comp, Umbrella — policy numbers for each |
| Policy Limits | Each occurrence, general aggregate, products-completed ops aggregate, personal injury |
| Policy Period | Effective and expiration dates of each policy |
| Certificate Holder | Entity receiving the certificate (e.g., City of Chicago) |
| Description of Operations Box | Where additional insured status, primary & non-contributory, and waiver of subrogation are noted |
| Cancellation Notice | Typical 30-day notice (10 days for non-payment) stated here |
⚠️ COI Best Practices: Always request a copy of the actual additional insured endorsement — not just the COI. Verify that the endorsement number matches an endorsement on file with the insurer. Check that the policy has not been cancelled or lapsed since the COI was issued. In construction and real estate, automated COI tracking systems (e.g., myCOI, Ebix, Certificial) are widely used to manage hundreds or thousands of vendor COIs.
Construction is the industry where additional insured requirements are most pervasive and most complex. Nearly every tier of the construction contract chain requires AI coverage:
| Party | Role in Contract Chain | AI Requirement |
|---|---|---|
| Property Owner | Hires General Contractor | Requires GC to name Owner as AI (ongoing + completed ops) |
| General Contractor (GC) | Prime contractor; manages subs | Requires each Subcontractor to name GC as AI (CG 20 10 + CG 20 37); GC is named as AI on owner’s policy |
| Subcontractor (Sub) | Performs specific trade work | Names GC and Owner as AI; may require Sub-Sub to name Sub as AI |
| Design Professional | Architect / Engineer | Professional liability (E&O) policy — AI endorsements generally not available; separate indemnity language used |
| Lender / Construction Bank | Finances construction | May require AI on builder’s risk and CGL; more commonly requires loss payee on builder’s risk |
✅ Industry Standard (AGC, AIA): The Associated General Contractors (AGC) and American Institute of Architects (AIA) standard contract forms (AIA A201, ConsensusDocs) require subcontractors to add general contractors and owners as additional insureds on CGL policies. Construction contracts routinely require both CG 20 10 and CG 20 37 to cover the full risk spectrum: claims during construction AND claims arising after construction is complete (e.g., structural defects, latent injuries).
Tail Coverage (Completed Operations)
One of the most litigated areas in construction AI coverage is completed operations (CG 20 37). Many construction defect claims arise years after project completion. The AI (GC or owner) may be sued for property damage or bodily injury from defective work completed by a subcontractor. Without a current CG 20 37 endorsement in force at the time of the claim, or a continuous-coverage endorsement from the policy period when the work was done, the AI may have no coverage under the named insured’s policy.
Commercial leases routinely require tenants to name landlords as additional insureds. Key lease-related AI issues include:
| Lease Requirement | Explanation |
|---|---|
| AI on Tenant’s CGL | Standard requirement: tenant names landlord as AI for bodily injury and property damage arising from tenant’s use of leased space |
| Minimum Limits | Leases typically specify minimum CGL limits (e.g., $1M/$2M); larger tenants or riskier uses may require $5M+ |
| Property Insurance | Separate from AI on liability; landlord typically requires tenant to maintain property insurance for tenant improvements and business personal property |
| Waiver of Subrogation | Most leases require both parties to waive subrogation rights against each other (prevents insurer from suing the other party after a covered loss) |
| ISO Form for Landlords | CG 20 11 (Additional Insured — Managers or Lessors of Premises) is the standard ISO form for the landlord/tenant AI relationship |
| Common Claim Scenario | A customer slips on a wet floor in tenant’s retail store and sues both the tenant and the landlord (as property owner). Landlord’s AI status triggers tenant’s CGL defense and indemnification for landlord. |
🏢 Real-World Lease AI Example
| Named Insured | Joe’s Coffee Shop LLC (tenant at 123 Main St.) |
| Policy Type | Commercial General Liability (CGL), $1M per occurrence / $2M aggregate |
| Additional Insured | Main Street Properties, LLC (landlord), per CG 20 11 endorsement |
| Trigger | Customer burns hand on defective coffee machine; sues both Joe’s Coffee Shop and Main Street Properties |
| Result | Joe’s CGL defends and indemnifies both Joe’s (named insured) and Main Street Properties (AI) under the single policy |
| Not Covered | If Main Street Properties were independently negligent (e.g., failed to fix a building code violation unrelated to tenant’s operations), ISO post-2013 forms may not cover that independent negligence |
Additional insured status alone may not fully protect the AI if both the named insured’s policy and the AI’s own policy respond to the same claim. To address this, contracts often require primary and non-contributory (P&NC) endorsements.
📄 Without P&NC
- Both the named insured’s policy AND the additional insured’s own policy respond
- Each insurer contributes pro-rata to the loss
- AI’s policy is eroded by claims arising from named insured’s work
- AI’s own limits depleted even though the named insured caused the claim
✅ With Primary & Non-Contributory
- Named insured’s policy is primary and pays first
- AI’s own policy is excess only — does NOT contribute until named insured’s policy is exhausted
- AI’s own limits are preserved for the AI’s own independent claims
- Most sophisticated construction and commercial contracts require P&NC
ℹ️ ISO CG 20 01: ISO endorsement CG 20 01 (“Primary and Noncontributory — Other Insurance Condition”) is the standard form used to make the named insured’s CGL primary and non-contributory with respect to the additional insured’s own policy. This is typically required in addition to the AI endorsement itself in commercial construction and real estate contracts.
Waiver of Subrogation
Many AI arrangements also include a Waiver of Subrogation, which prevents the insurer (after paying a claim) from “stepping into the shoes” of the insured and suing the additional insured to recover the payment. ISO endorsement CG 24 04 provides a blanket waiver of subrogation for CGL policies. Without this waiver, an insurer who pays a claim could potentially sue the AI to recover its payment — defeating the purpose of the AI arrangement.
While CGL is the most common policy for AI endorsements, additional insured status can be added to other commercial lines:
| Policy Type | AI Availability | Common Use Case |
|---|---|---|
| Commercial Auto | Yes — via endorsement (ISO CA 20 48) | Lessors of vehicles; entities hiring contractors who use autos; vehicle loan agreements |
| Umbrella / Excess Liability | Yes — required to “follow form” to underlying CGL AI coverage | Construction contracts requiring AI on umbrella; large commercial leases requiring high limits |
| Employer’s Liability | Limited — “Alternate Employer Endorsement” adds coverage for temporary employees; not traditional AI | Staffing agencies; leased employee arrangements |
| Professional Liability (E&O) | Generally NO — P/L policies are claims-made, personal to the insured, non-assignable; AI endorsements not standard | Design-build contracts use indemnification provisions instead |
| Workers’ Compensation | No — WC is a statutory benefit for employees; AI concept does not apply | Alternate Employer endorsement used for borrowed/leased employees |
| Cyber Liability | Emerging — some carriers offer AI endorsements for third-party tech service providers | Cloud vendors; data processors; managed service providers |
| Builder’s Risk | Yes — property policy; all insured parties listed as named insureds or additional named insureds | Owner, GC, and lender all named on builder’s risk during construction |
Common Mistakes
| Mistake | Consequence |
|---|---|
| Accepting a COI without verifying the actual AI endorsement exists | No coverage exists when a claim arises; discovery after loss is too late |
| Confusing “certificate holder” with “additional insured” | Party believes they are covered; insurer denies claim because no endorsement was issued |
| Failing to require CG 20 37 (completed operations) in construction | Post-construction defect claims have no AI coverage because only CG 20 10 (ongoing) was obtained |
| Accepting COIs for expired policies | Coverage gap — policy lapsed but COI from prior year still on file; claims not covered |
| Not requiring P&NC endorsement in contract | AI’s own policy eroded by claims caused by named insured’s negligence |
| Relying on blanket AI endorsements without verifying scope | Blanket endorsements may not cover all contractual AI requirements; manual review needed |
| Failing to track COI renewals annually | Annual policies expire; subcontractor may renew with a different insurer without notification; coverage lapses |
Best Practices for Risk Managers and Contractors
- Require both CG 20 10 and CG 20 37 in all construction subcontracts — never accept only one
- Require P&NC and Waiver of Subrogation by contract and verify endorsements match
- Request actual endorsement copies, not just COIs — file them with project records
- Use automated COI tracking software (myCOI, Ebix, Certificial, Procore Insurance) for high-volume vendor relationships
- Specify minimum limits in contracts (e.g., $1M/$2M CGL, $5M umbrella for major projects)
- Review AI endorsements with coverage counsel after 2013 ISO form revisions to ensure contractual requirements are met by actual endorsement language
- Track annual renewals — build COI expiration dates into project management and vendor databases
An additional insured is a person or entity granted coverage under another party’s insurance policy — typically through an endorsement — at the named insured’s request. The most common examples are landlords added to a tenant’s general liability policy, or general contractors added to a subcontractor’s CGL policy. The additional insured is protected against third-party claims arising from the named insured’s operations.
The named insured is the primary policyholder who purchased the policy and has full policy rights. The additional insured is a secondary party granted limited coverage under the named insured’s policy through an endorsement. Key differences: named insureds pay the premium and have full policy rights; additional insureds receive coverage only for claims arising from the named insured’s operations (not their own independent negligence, under post-2013 ISO forms) and have more limited policy rights.
An additional insured is added via a policy endorsement — a written amendment to the policy. The named insured requests the insurer to issue an endorsement (most commonly an ISO form like CG 20 10 or CG 20 37 for CGL policies). The endorsement is the legal instrument that creates AI coverage — not the Certificate of Insurance. Most contracts specify which ISO form is required and what policy limits must be maintained.
Yes — but the COI (typically ACORD Form 25) is evidence of the coverage, not the coverage itself. The AI is listed in the “Description of Operations” box, which notes the AI endorsement. However, the actual coverage is determined by the endorsement language, not the COI. Always request the actual endorsement in addition to the COI to verify scope and terms.
CG 20 10 covers the additional insured for liability arising from the named insured’s ongoing (in-progress) operations. CG 20 37 covers liability from completed operations — work already finished. In construction, general contractors typically require both: CG 20 10 to cover the period during construction, and CG 20 37 to cover post-construction defect claims that can arise years after project completion.
Primary and non-contributory (P&NC) means the named insured’s policy is primary — it pays first — and will NOT seek contribution from the additional insured’s own policy. Without P&NC, both insurers share the claim pro-rata, depleting the AI’s own limits even for losses caused by the named insured. P&NC protects the AI’s own policy limits from erosion by claims that should be the named insured’s responsibility. ISO endorsement CG 20 01 is used to add P&NC.
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