Additional Insured Endorsements Every Business Should Know

If you work in construction, property management, real estate, or any industry where contracts require insurance provisions, you've encountered additional insured endorsements. But not all additional insured endorsements are the same. The insurance industry uses dozens of standardized endorsement forms, each designed for a specific relationship and a specific type of risk. Using the wrong form — or not understanding what your endorsement actually covers — can leave the additional insured without the protection they expected, create disputes when claims are filed, and put your contractual compliance at risk. This guide covers the most important additional insured endorsement forms, what each one is designed for, and when to use them.

Why the Specific Endorsement Form Matters

All additional insured endorsements extend some degree of liability coverage to a third party under your policy. But the scope of that coverage varies significantly depending on which endorsement form is used. Some forms cover only ongoing operations. Others extend through the completed operations period. Some limit coverage to claims arising from "your work." Others use broader language that captures a wider range of situations.

The endorsement form also affects how coverage disputes are resolved. When a claim is filed and the additional insured seeks coverage under your policy, the carrier will look at the specific endorsement language to determine whether the claim falls within the endorsement's scope. The wrong form can mean the difference between the additional insured being defended and the additional insured being told the claim isn't covered.

Contracts often specify which endorsement forms are required — sometimes by ISO form number. Understanding what each form covers helps you verify that your policy meets your contractual obligations and helps you have informed conversations with your agent about your coverage needs.

CG 20 10: Owners, Lessees, or Contractors — Ongoing Operations

The CG 20 10 is the most widely used additional insured endorsement in commercial insurance. It's the standard form for construction projects, service contracts, and any situation where one party hires another to perform work.

What It Covers

The CG 20 10 provides additional insured coverage for bodily injury and property damage caused by your ongoing operations — meaning the work you're actively performing. If you're a subcontractor on a construction site and a third party is injured because of your work while it's in progress, the CG 20 10 extends your GL coverage to the additional insured (typically the GC or project owner) for that claim.

What It Does Not Cover

The CG 20 10 does not cover claims arising after your work is completed. Once you finish the project, pack up your tools, and leave the site, the ongoing operations coverage under CG 20 10 ends. If a defect in your work causes injury or damage months or years later — a roof leak, a plumbing failure, an electrical issue — the CG 20 10 will not provide coverage to the additional insured for that completed operations claim.

This is a critical limitation. In construction, many of the most serious and expensive claims are completed operations claims — defects that don't manifest until long after the work is done. The CG 20 10 alone leaves a significant gap for these types of losses.

When It's Used

The CG 20 10 is used in virtually every construction subcontract, many service agreements, and most vendor contracts. It's the baseline additional insured endorsement that nearly every GC, property owner, and client will require.

CG 20 37: Owners, Lessees, or Contractors — Completed Operations

The CG 20 37 is the companion form to the CG 20 10. While the CG 20 10 covers ongoing operations, the CG 20 37 extends additional insured coverage into the completed operations period — after the work is finished.

What It Covers

The CG 20 37 covers bodily injury and property damage that arises from your completed work. If you finished a plumbing installation six months ago and a pipe joint you installed fails, causing water damage to the building and injury to an occupant, the CG 20 37 extends your GL coverage to the additional insured for that claim.

Why It Matters

Completed operations coverage is essential in construction and trades. Construction defect claims are among the highest-severity claims in commercial insurance, and they often don't surface until months or years after the work is done. Without a CG 20 37, the additional insured has no coverage under your policy for these claims — they'd need to rely on their own insurance and then pursue you directly for recovery.

How It Works with CG 20 10

The CG 20 10 and CG 20 37 are almost always required together. The CG 20 10 covers claims during the project. The CG 20 37 covers claims after the project is complete. Together, they provide continuous additional insured coverage from the start of work through the completed operations period.

Most well-drafted construction contracts specify both forms by number: "CG 20 10 and CG 20 37, or equivalent." If a contract only requires CG 20 10, the additional insured may not realize they're missing completed operations coverage — a gap that could prove costly.

CG 20 11: Managers or Lessors of Premises

The CG 20 11 is designed specifically for the landlord-tenant relationship. It adds the property owner, lessor, or property manager as an additional insured on the tenant's GL policy.

What It Covers

The CG 20 11 covers the landlord or property manager for liability claims arising from the tenant's use of the premises — and only the premises. If a customer slips and falls in the tenant's store, the landlord can be covered under the tenant's policy through this endorsement. If a tenant's operations cause a fire that damages the building and injures someone, the CG 20 11 allows the landlord to access the tenant's GL coverage.

How It Differs from CG 20 10

The CG 20 11 is premises-specific. Coverage is tied to the tenant's use and occupancy of the leased space, not to a broader scope of operations. The CG 20 10, by contrast, is operations-specific — it covers claims arising from the named insured's work, wherever that work occurs.

For a tenant operating a retail store in a leased space, the CG 20 11 is the appropriate form. For a contractor performing renovation work in that same building, the CG 20 10 (and CG 20 37) would be the appropriate forms.

When It's Used

Commercial leases almost universally require tenants to add the landlord as additional insured. The CG 20 11 is the standard form for this purpose. It's also used when a property management company needs to be listed as additional insured on the policies of the properties they manage.

CG 20 26: Designated Person or Organization

The CG 20 26 is a broader additional insured endorsement that names a specific person or organization and provides coverage for claims arising from the named insured's operations, without some of the more restrictive language found in other forms.

What It Covers

The CG 20 26 covers the designated person or organization for bodily injury and property damage liability arising from the named insured's (your) operations. The language is relatively broad compared to some other forms, making it versatile for situations that don't fit neatly into the contractor/owner or landlord/tenant categories.

When It's Used

The CG 20 26 is often used for miscellaneous additional insured requests that don't fit the construction or landlord-tenant mold — business partnerships, joint ventures, professional service relationships, or any situation where the requesting party needs additional insured coverage but the relationship isn't specifically addressed by a more targeted endorsement form.

Some carriers also use the CG 20 26 as their default scheduled additional insured form when a more specific form isn't requested.

CG 20 15: Vendors

The CG 20 15 is designed for manufacturers and distributors who need to add downstream vendors (retailers, wholesalers, distributors) as additional insureds on their products liability coverage.

What It Covers

The CG 20 15 covers the vendor for liability arising from the named insured's products — specifically, products that the vendor distributes or sells. If a manufacturer adds a retail chain as additional insured under CG 20 15, and a consumer is injured by the manufacturer's product purchased at that retail chain, the manufacturer's GL policy covers the retailer through this endorsement.

Limitations

Coverage under the CG 20 15 is limited to the vendor's role as a distributor or seller of the named insured's products. It does not cover the vendor for claims arising from the vendor's own operations, negligence, or modifications to the product. If the vendor alters the product, repackages it, or fails to follow the manufacturer's handling instructions, the CG 20 15 coverage may not apply.

When It's Used

The CG 20 15 is common in manufacturing, distribution, and retail relationships. Manufacturers use it to provide downstream coverage to their distribution partners, which helps maintain those business relationships and satisfies the additional insured requirements in distribution and sales agreements.

CG 20 12: State or Governmental Agency or Subdivision or Political Subdivision

The CG 20 12 adds a state, county, city, or other governmental entity as an additional insured on your policy.

When It's Used

Government contracts and permits frequently require contractors, vendors, and service providers to add the governmental entity as additional insured. Public works projects, road construction, utility work, park maintenance, and any work performed under a government contract or permit may trigger this requirement. The CG 20 12 is specifically designed for these relationships and uses language appropriate for governmental entities.

CG 20 33: Owners, Lessees, or Contractors — Automatic Status When Required by Written Contract

The CG 20 33 is a blanket additional insured endorsement specifically for the construction and contractor relationship. Unlike the scheduled CG 20 10, which names a specific party, the CG 20 33 automatically extends additional insured status to any owner, lessee, or contractor that you're required to add by written contract.

How It Relates to CG 20 10

The CG 20 33 is functionally the blanket version of the CG 20 10. It covers ongoing operations and applies automatically based on your contractual obligations. For completed operations coverage under a blanket arrangement, carriers may offer CG 20 37 in blanket form or use a proprietary endorsement that combines blanket ongoing and completed operations coverage.

When It's Used

The CG 20 33 is the go-to blanket endorsement for contractors who work with multiple GCs, project owners, and clients throughout the year. It eliminates the need to process individual CG 20 10 endorsements for each project while providing the same scope of coverage.

Choosing the Right Endorsement

Selecting the right additional insured endorsement starts with understanding the relationship and the contract requirements.

For construction and contractor relationships: CG 20 10 (ongoing) and CG 20 37 (completed operations), or their blanket equivalents.

For landlord-tenant relationships: CG 20 11.

For product distribution and vendor relationships: CG 20 15.

For government contracts: CG 20 12.

For general or miscellaneous relationships: CG 20 26.

For blanket coverage across multiple contracts: CG 20 33 (or carrier-proprietary blanket forms).

When a contract specifies endorsement forms by number, use those specific forms. When a contract simply requires "additional insured status" without specifying a form, work with your agent to select the appropriate endorsement based on the nature of the relationship.

Common Pitfalls

Using only CG 20 10 when completed operations is needed. This is the most common mistake in construction insurance. If you only provide ongoing operations coverage and a defect claim surfaces after the project is done, the additional insured has no coverage under your policy.

Using the wrong form for the relationship. A CG 20 11 (premises) won't work for a contractor performing off-site work. A CG 20 10 (operations) doesn't properly address a landlord-tenant relationship. Matching the form to the relationship ensures the coverage applies when it's needed.

Assuming all blanket endorsements are equal. Blanket additional insured endorsements vary by carrier. Some cover ongoing and completed operations. Some cover only ongoing. Some limit coverage to the minimum required by contract. Some extend to full policy limits. Read the endorsement language carefully.

Not verifying endorsement forms against contract requirements. If a contract requires CG 20 10 and CG 20 37 and you provide a CG 20 26, you may technically be out of compliance — even though the CG 20 26 provides coverage. Some clients will accept equivalent forms; others will insist on the exact forms specified.

Getting Your Endorsements Right

Additional insured endorsements are a fundamental part of commercial insurance for contractors, property managers, manufacturers, and service businesses. The specific forms you need depend on your industry, your contracts, and your business relationships. Getting the right endorsements in place — and understanding what each one actually covers — protects both you and the parties you work with.

At SmartInsured, we help Washington businesses navigate additional insured requirements, select the right endorsement forms, and set up policies that meet contractual obligations from day one. If you're unsure whether your current endorsements match what your contracts require, let us review your coverage and make sure everything is in order.