An additional insured endorsement adds another person or organization, a landlord, general contractor, or project owner, to your general liability policy, giving them insured status for claims caused, in whole or in part, by your work or your acts and omissions. It does not cover the additional insured's own sole negligence, it does not increase your policy limits, and different endorsement forms cover very different slices of a project: CG 20 10 covers ongoing operations, while CG 20 37 covers completed operations.
If you sign construction contracts or commercial leases, you have almost certainly been asked for one. Here is what the request actually means, grounded in the ISO forms most insurers use.
Additional Insured Endorsement
An additional insured endorsement adds another person or organization, such as a landlord or general contractor, to your general liability policy, giving them insured status for claims caused in whole or in part by your work or your acts and omissions. It does not cover their sole negligence and does not increase the policy's limits.
What is an additional insured?
The CGL policy automatically insures certain people, the named insured, and automatic insureds like employees acting within their duties (see what general liability insurance covers for the full list). An additional insured is a third category: a person or organization deliberately granted insured status by endorsement, based on a business relationship. Additional insureds generally fall into three groups:
- An entity to whom the named insured provides services, a project owner or general contractor hiring a subcontractor
- The owner of premises or equipment the named insured uses or leases, a landlord, or an equipment lessor
- A party with an ownership or financial interest, a lender or mortgage holder
Why do businesses request additional insured status?
The reasons are practical, not paranoid:
- A safety net behind the contract: contracts usually pair a hold-harmless/indemnification clause with an additional insured requirement, the "belt and suspenders" approach. If a statute or court decision invalidates the indemnity clause, the endorsement still stands.
- Defense costs outside the limits: an additional insured that meets its policy duties gets its defense paid as a supplementary payment, outside the limit of insurance, the same treatment the named insured receives.
- Protection from subrogation: insurers generally do not subrogate against other insureds on the same policy, so paying a claim will not lead the named insured's carrier to chase the additional insured for reimbursement.
- Access to another set of limits: the additional insured can reach the named insured's limits before touching its own, especially when the endorsement is paired with primary and noncontributory wording.
- Potentially better rates and underwriting treatment: a party that contractually pushes primary responsibility to others may pay less for its own coverage, and insurers may view the practice as proactive risk management.
CG 20 10 vs. CG 20 37: ongoing vs. completed operations
The two most requested forms split a construction project in half at completion:
| Feature | CG 20 10 12 19 | CG 20 37 12 19 |
|---|---|---|
| Full title | Additional Insured: Owners, Lessees Or Contractors, Scheduled Person Or Organization | Additional Insured: Owners, Lessees Or Contractors, Completed Operations |
| Covers | Injury or damage caused in whole or in part by your acts or omissions during ongoing operations for the additional insured | Injury or damage caused in whole or in part by your work, within the products-completed operations hazard |
| Coverage lines | Bodily injury, property damage, and personal and advertising injury | Bodily injury and property damage |
| Written contract required by the form? | No, the party is scheduled | No, the party is scheduled |
| Completed operations? | Excluded: coverage stops once the work is completed or put to its intended use | That is the point |
CG 20 10 shuts off when the project is finished, and construction claims routinely surface after completion. That's why contracts commonly require both endorsements, often with the CG 20 37 maintained for two or three years after completion, or for the statute of repose period. That post-completion exposure is the same one that makes builders risk and completed-operations planning so important for contractors.
What about automatic additional insured status?
Scheduling every party on every project gets unwieldy, so ISO publishes "automatic status" versions that grant additional insured status whenever a written contract or agreement requires it:
- CG 20 33: automatic status for ongoing operations, for parties you contract with directly
- CG 20 38: automatic status for ongoing operations, extending to other parties (like a project owner) named in your customer's contract, even if they never signed anything with you
- CG 20 39 and CG 20 40: the completed-operations counterparts to CG 20 33 and CG 20 38
The automatic construction forms carry a notable exclusion: no coverage for liability arising out of professional architectural, engineering, or surveying services, an exclusion that applies even when the claim alleges negligent supervision, hiring, or training connected to those services.
Other relationship-specific forms exist too: CG 20 11 for managers or lessors of premises, CG 20 28 and CG 20 34 for equipment lessors, CG 20 15 and CG 20 44 for vendors, and CG 20 26 as a designated-person form best reserved for relationships no specific form fits. One additional insured may require several endorsements simultaneously.
What additional insured status does not do
ISO tightened these forms substantially in 2004 and after, and the limitations matter on both sides:
- No coverage for the additional insured's sole negligence. The 2004 revision changed "arising out of" to "caused by," requiring a causal connection to the named insured's acts, omissions, or work.
- No increase in limits. Every insured, named and additional, shares the same limits, with no priority for anyone.
- No broader coverage than the contract requires. Recent editions pay the lesser of the amount the contract requires or the available limits.
- No control of the defense. The named insured's carrier investigates, defends, and settles. The additional insured has no direct say, and defending both parties can create genuine conflicts of interest when each side's best defense is blaming the other.
If you are protected only as an additional insured, you are exposed to that policy's exclusions, its cancellation or nonrenewal, and its aggregate limits being quietly eroded by other claims, with no notice to you. Additional insured status supplements your own CGL, it never replaces it.
What does "primary and noncontributory" mean?
Contracts usually add a second request: that the named insured's coverage be primary and noncontributory. Per IRMI's definition, noncontributory insurance "will not seek contribution from other insurance policies that apply to a covered loss on the same basis." Without it, the CGL's Other Insurance condition may put two primary policies into a sharing arrangement, equal shares if the other policy permits it, otherwise pro rata by limits.
On a $300,000 loss between a $500,000 policy and a $1,000,000 policy, equal shares means $150,000 each, while pro rata splits it $100,000 and $200,000. Either way, the additional insured's own policy is paying.
The fix is the Primary And Noncontributory: Other Insurance Condition endorsement (CG 20 01 12 19), which modifies the Other Insurance condition so the named insured's policy responds first and does not seek contribution from the additional insured's insurance, subject to a written contract requiring it.
How to handle an additional insured request
When a contract lands with an additional insured requirement, work through it in this order:
Read the insurance requirements exhibit
Identify exactly which parties must be added, which form numbers or edition dates are specified, whether completed operations coverage is required, and for how long after the project.
Match forms to the relationship
Landlord requests point to CG 20 11, construction relationships to the CG 20 10/20 37 family or their automatic-status equivalents, and equipment and vendor relationships to their specific forms.
Add primary and noncontributory wording where required
If the contract requires it, confirm CG 20 01 (or equivalent carrier wording) is attached rather than assuming the base policy delivers it.
Evidence it correctly
The other party will want proof, typically a certificate of insurance with the endorsements attached. Remember that a certificate alone confers no coverage, the endorsement does.
Frequently asked questions
What's the difference between an additional insured and a certificate holder?
A certificate holder merely receives a certificate of insurance as evidence that coverage exists, the certificate grants no rights under the policy. An additional insured is actually endorsed onto the policy and has insured status, including a defense and access to the policy's limits for covered claims.
Does an additional insured endorsement cover the additional insured's own negligence?
Partially. Current ISO editions cover the additional insured for injury or damage caused in whole or in part by the named insured, which includes joint negligence of both parties. What is not covered is a loss caused by the additional insured's sole negligence.
Do I need both CG 20 10 and CG 20 37?
On construction projects, usually yes if the contract requires completed operations coverage. CG 20 10 stops at completion, and CG 20 37 picks up the products-completed operations hazard afterward. Many contracts require maintaining the completed-operations endorsement for years after the work is done.
Does adding additional insureds increase my policy limits?
No. All insureds share the same limits of insurance, and the endorsements state they do not increase the applicable limits. Each additional insured is one more party drawing on the same pool, a reason to revisit whether your limits and umbrella are adequate.
This guide is for educational purposes and summarizes standard ISO policy language. Your policy's specific terms, conditions, and endorsements control. Talk to a licensed broker about your actual exposures.