Additional insured explained: an additional insured is a person or business added to someone else’s insurance policy, usually by a formal endorsement, so it receives limited protection against liability claims arising from the named insured’s work. It is not a co-owner of the policy, and it is not the same as being named in a certificate of insurance.
That distinction trips up more people than anything else in commercial insurance. A general contractor sees a checkbox on a certificate and assumes the job is done. A landlord signs a lease requiring tenant insurance and assumes the building is protected. Both assumptions can be wrong at the worst possible moment.
The rest of this guide walks through how the endorsement works, which coverage it actually provides, which forms insurers use, what the status does not cover, and how to verify it before you rely on it. Rules differ by state and change as policy forms are revised, so treat this as a working explanation rather than legal or insurance advice.
Last updated: October 2026
Table of Contents
- What Is an Additional Insured?
- Named insured, co-insured, beneficiary, additional interest
- How Does an Additional Insured Endorsement Work?
- Who requests the endorsement
- What the insurer does before issuing it
- What the other party actually receives
- What Does an Additional Insured Endorsement Cover?
- Additional Insured vs. Co-Insured or Additional Interest
- Common Additional Insured Endorsement Forms
- What Additional Insured Status Does Not Automatically Cover
- Limits, Deductibles and Other Policy Conditions
- Primary and non-contributory
- Shared limits and aggregate erosion
- Other insurance
- Notice, cancellation and documentation
- How to Add an Additional Insured to Your Policy
- What to Check Before Relying on the Endorsement
- Frequently Asked Questions
- Is an additional insured covered for free?
- Does a certificate of insurance prove I am an additional insured?
- Can a contractor require me to add them as an additional insured?
- Does an additional insured endorsement cover the named insured’s negligence?
- Can an individual driver be an additional insured?
- Why was my additional insured claim denied?
- Conclusion
What Is an Additional Insured?
An additional insured is a party named on a liability policy that has limited rights to that policy’s coverage. The named insured buys the policy and owns it. The additional insured gets a slice of it, usually tied to claims caused by the named insured’s operations.
Status comes from an endorsement attached to the policy, not from a conversation, a contract clause, or a PDF emailed to you. The carrier issues the endorsement and then issues a certificate showing it. The certificate describes the endorsement; it does not create one.
Named insured, co-insured, beneficiary, additional interest
Four other terms show up in the same paperwork and mean four different things. A named insured is the policyholder with full rights, including the right to change, cancel and receive the return premium. A co-insured usually holds equal rights to the named insured. A beneficiary is named to receive payment on a loss, which matters for property policies rather than liability ones.
An additional interest is simply told, in writing, that something happened. A mortgagee’s loss payee, a lienholder or a lender often gets a notice of cancellation. That notice carries no right to defend a claim or collect money. Businesses ask for this status because it feels protective, and then assume it is the same thing. It is not.
The reason a landlord, general contractor or event organizer asks for it comes down to cost. Without it, the property owner pays the defense costs and the settlement out of pocket, then tries to recover from the contractor that caused the problem. With it, those costs land on the contractor’s insurer instead. That is the whole idea.
How Does an Additional Insured Endorsement Work?
The process is short, and every step matters. Skipping one is why certificates circulate without endorsements behind them.
Who requests the endorsement
The named insured requests it, not the party being added. A general contractor’s insurance agent adds the property owner, because the property owner has no policy relationship with the subcontractor’s carrier. If you have been asked to be an additional insured, you are the beneficiary of the request; the policyholder still has to act.
What the insurer does before issuing it
The carrier underwrites it like any other policy change. It reviews the endorsement wording, the operations being covered, whether the relationship is described in a written contract, and how much limit is exposed to the added party. Some carriers charge an endorsement fee or adjust the premium. Many charge nothing for a straightforward addition.
What the other party actually receives
Two documents, and only one of them matters. The endorsement is a page attached to the policy that modifies its terms; that is the coverage. The certificate of insurance, usually issued on an ACORD 25 form, is a summary that reports what the policy says. If the two ever disagree, the policy and its endorsements govern.
The chain looks like this: written contract creates the requirement, the policyholder requests the endorsement, the carrier issues the endorsement, the certificate reports it, and someone verifies the wording. Skip any link and the requirement is only partly met.
What Does an Additional Insured Endorsement Cover?
What you get depends entirely on the policy type and the wording of the endorsement attached to it. A general liability additional insured provision and a commercial auto one behave very differently.
- General liability: typically bodily injury, property damage, personal and advertising injury, and the defense costs tied to claims the named insured caused. Many forms also add indemnification obligations owed by the named insured under a written contract.
- Property damage: some property forms add an owner as an additional insured for covered loss to their interest in the property. This does not mean the named insured’s policy pays for everything that happens to the building.
- Personal and advertising injury: included on many general liability forms, including offenses like libel, slander and false advertising. Coverage here varies by form.
- Commercial auto: a separate endorsement, often with the owner listed for a specific vehicle or for the whole fleet. Designated insured for that vehicle status is what drivers talk about.
- Umbrella and excess: excess liability policies carry their own additional insured endorsements, usually following the underlying general liability wording.
Notice what is missing from that list: the added party’s own property, their own professional errors, and their own independent mistakes. Insurance coverage for those things lives in their own policies, if anywhere.
Additional Insured vs. Co-Insured or Additional Interest
This table answers more search questions than anything else on the topic, because the same certificate lists four of these labels and readers assume they are interchangeable.
| Role | What it means | Liability coverage | What you can do |
|---|---|---|---|
| Named insured | The policyholder named in the declarations | Full, subject to policy terms | Cancel, change, amend, sue on behalf of the policy |
| Additional insured | A party given limited rights by endorsement | Yes, only as the endorsement states | Present a claim for covered loss within the stated scope |
| Co-insured | A party with rights close to the named insured | Usually broad | Rights are set out in the policy, often for LLC members or spouses |
| Additional interest | A party notified of cancellation or material change | None | Receive notice; nothing else |
| Certificate holder | A party requesting proof of insurance | None | Read the certificate; enforce contract terms |
| Designated insured for auto | A driver given broader auto rights on a scheduled vehicle | Yes, on that vehicle, per the endorsement | Claim for loss involving the scheduled vehicle |
| Waiver of subrogation | A party whose insurer agrees not to sue another party | None directly; it blocks a recovery route | Rely on the waiver when a covered loss occurs |
| Lienholder or loss payee | A party with a financial interest in covered property | None for liability | Receive payment up to the stated amount |
The practical difference between the two columns people confuse most: a certificate holder is a mailbox, and an additional interest is a courtesy letter. An additional insured is the only one of the three with a claim right.
Common Additional Insured Endorsement Forms
Most carriers write endorsements on ISO forms, which have numbers and edition dates. The edition matters: an older edition can leave a gap that the newer one closes. Carriers also file their own modified versions, and state law can require language different from the ISO original.
| Form | Typical use | Ongoing operations | Completed operations |
|---|---|---|---|
| CG 20 10 | Owner, general contractor, landlord added to a subcontractor’s general liability policy | Usually covered | Covered if the edition includes completed operations |
| CG 20 37 | Mutual waiver of subrogation between two parties | Not a coverage grant | Not a coverage grant |
| CG 20 26 | Owner, general contractor or other party added as a co-insured with full additional insured rights | Covered | Covered, subject to wording |
| CG 20 37 04 13 and later editions | Updated waiver wording; check the edition stamp on your copy | Varies by edition | Varies by edition |
| CA 20 48 or similar auto forms | Designated insured for scheduled autos | Applies to the listed vehicle | Not applicable |
CG 20 10 is the one that comes up in almost every conversation about construction. The 2013 edition is the widely circulated version, and later insurer-filed editions exist. Read the edition line on the form itself, because that is the version controlling your claim.
What Additional Insured Status Does Not Automatically Cover
Most disputes are not about whether the endorsement exists. They are about what it covers once it does.
- The added party’s own negligence. If the landlord’s own crew leaves a gate open, the landlord’s status on the contractor’s policy does not answer for it.
- Intentional acts. Liability coverage generally excludes liability arising from intentional or criminal acts. That exclusion usually follows the additional insured as well.
- Breach of contract on its own. A failure to perform is a contract problem. Coverage responds to a resulting bodily injury or property damage claim, not to the missed deadline.
- Professional design errors. Design-bug claims are argued over constantly. Some additional insured endorsements include design-related coverage on a limited basis; many do not.
- Deductibles and self-insured retentions. A retained amount is usually the named insured’s to pay. The added party pays the rest.
- Limits already used. Additional insured shares the same limits as the named insured. They do not get their own limit stack.
- The property itself. Tenant insurance on a rented unit can name the owner, but the owner’s building is not covered for damage caused by, say, a frozen pipe in cold weather.
Courts have read these boundaries differently across states, including on the question of an added party’s independent acts of negligence. That is exactly the kind of question to take to an attorney rather than a blog post.
Limits, Deductibles and Other Policy Conditions
Four conditions decide whether a real claim gets paid, and none of them show up in a certificate summary.
Primary and non-contributory
This wording tells other insurers that this policy responds first and that the added party does not have to share in the other carrier’s limits. Without it, a property owner with its own liability policy could find the two carriers splitting the same dollar. If your contract requires it, confirm it appears in the endorsement and not just in the certificate.
Shared limits and aggregate erosion
Each additional insured draws on the same per-claim and aggregate limits as the named insured. Two claimants against one policy can exhaust the aggregate, and the second one waits. Aggregate limits also reset only at renewal, not after each claim.
Other insurance
An other insurance provision decides how two policies covering the same loss share it. Commercial auto policies are frequently primary. Uninsured and underinsured motorist provisions behave differently again. This is where the primary and non-contributory language earns its keep.
Notice, cancellation and documentation
Certificates expire with the policy period, often with no reminder to anyone. Ask to be named as a notice recipient, in writing, so the carrier tells you before the endorsement disappears. A general contractor who found out about a lapse from a lien is a familiar and expensive story.
How to Add an Additional Insured to Your Policy
Eight steps, in order. Most of them are one email.
- Read the contract clause. Find the exact wording requiring additional insured status. The contract often specifies the form number, the edition, the limit basis and primary and non-contributory language. That specification is your instruction.
- Get the legal name and address right. Use the exact entity name from the state registry. A DBA, a division or a slightly different LLC name can cause a denial later. Members of a single-member LLC may also need to be added individually.
- Confirm which policy carries the endorsement. Generally it belongs on the general liability policy for liability work, on the auto policy for vehicle exposure, and often on both when both are involved.
- Ask your agent or broker in writing. State the party, the operations covered, the limit basis and whether blanket or scheduled wording is acceptable.
- Ask for the endorsement form itself. Request the actual form with its edition date, not just the certificate. This is the step that separates real coverage from a checkbox.
- Ask about the fee. Small additions are frequently free, though some carriers charge an endorsement fee or adjust the premium. If a carrier refuses outright, that is worth asking about.
- Review the wording before accepting the job contract. Check ongoing versus completed operations, primary and non-contributory language, and whether limits are shared.
- Collect, date-stamp and track. Store the certificate and the endorsement together, calendar the expiration, and request an updated certificate at renewal.
A short note to your agent usually does the job: “Please add [exact legal name, address] as an additional insured on our general liability policy for [operations], primary and non-contributory, ongoing and completed operations, using CG 20 10. Please send the endorsement form and a certificate.”
What to Check Before Relying on the Endorsement
Whether you are the policyholder collecting proof or the contractor handing it over, the same seven checks apply.
- Exact legal name. Entity type, state and address must match. A DBA is not the named entity.
- Form number and edition date. Note both, and confirm which edition the contract required.
- Effective date. It must cover the date of the loss or the date of the operations, not just today’s date.
- Covered operations. Ongoing operations, completed operations, or both.
- Limit basis. Per occurrence, per claims-made aggregate, and whether it shares the named insured’s limits.
- Cancellation notice. Whether you are named to receive notice, and how much advance warning you get.
- Certificate versus endorsement. Confirm the certificate’s AI box matches the actual endorsement, with no gap between the two.
That last item is the one practitioners on LinkedIn and in trade groups repeat most often: a COI is not proof of coverage. A certificate can show a party as additional insured while the underlying policy never received the endorsement. Request the form.
Frequently Asked Questions
Is an additional insured covered for free?
Often yes. Adding a property owner, general contractor or similar party to a general liability policy is frequently done at no charge, because the exposure is modest and the added party does not own the policy. Some carriers charge a flat endorsement fee or adjust the premium at renewal, especially for blanket wording or scheduled listings. Ask your agent for the fee before the work starts rather than after. If a carrier refuses to add the party at all, ask why in writing, since contract clauses often require it.
Does a certificate of insurance prove I am an additional insured?
No. A certificate is a summary document that reports what a policy says. It is not the policy, and a checkbox on it does not create coverage. Only the endorsement attached to the policy grants additional insured status. Certificates can also expire at the policy renewal while the underlying endorsement continues, or show an AI box with no matching endorsement on file. The reliable move is to request the endorsement form itself, with its number and edition date.
Can a contractor require me to add them as an additional insured?
Yes, that is extremely common. General contracts, leases and vendor agreements routinely require it, because it shifts the cost of defending and paying claims to the contractor’s insurer instead of the owner’s checkbook. As the owner or property owner, the request usually runs the other direction, with your contractor agreeing to add you. What matters is whether the contract specifies the form number, the edition, the limit basis and whether primary and non-contributory wording is required.
Does an additional insured endorsement cover the named insured’s negligence?
The endorsement covers claims arising from the named insured’s work, including claims where the named insured’s negligence caused the harm. It does not cover the added party’s own independent negligent acts. If the property owner’s own crew causes the damage, that party cannot claim against the contractor’s policy for its own mistake, and its own liability policy is the place to look. Several courts have addressed this boundary on independent acts of negligence, and results vary by state.
Can an individual driver be an additional insured?
On an auto policy, the usual vehicle for an individual is designated insured for a scheduled auto, which grants broader rights on that specific vehicle than ordinary additional insured status. The endorsement names the driver, ties them to a listed vehicle, and often extends to the vehicle’s ownership rather than the person’s driving everywhere. Because the wording differs by carrier, ask for the form and read it. Commercial auto liability for the business is a separate question from the individual driver’s status.
Why was my additional insured claim denied?
The usual reasons are mechanical. The endorsement was never actually issued and only a certificate existed. The legal name on the certificate did not match the entity that suffered the loss. The loss occurred after completed operations ended, or after the certificate expired. The claim fell to the added party’s own negligence or to an exclusion such as an intentional act. Or the limits were already exhausted by an earlier claim, since additional insureds share the named insured’s limits.
Conclusion
If you take one action from this guide, make it this: ask whoever holds the policy for the actual endorsement form, with its number and edition date, instead of accepting a certificate on its own. That single request closes most of the gaps described above, and it costs one email.
From there, check the legal name against your state registry, confirm the covered operations and the limit basis, and put a reminder in your calendar for the renewal date. Insurance rules vary by state and policy, so confirm your own situation with a licensed agent or attorney before relying on any of this.
