What Is an Additional Insured in Contractor Insurance?
Additional insured is one of the most requested and least understood terms in contractor insurance. GCs require it from every subcontractor on commercial projects. Property owners require it as a condition of contract. And most contractors providing it do not fully understand what they are granting or what it exposes their policy to.
This article covers what additional insured status actually is, why it is required, the endorsement forms that matter, and what it costs. For how additional insured requirements show up on certificates, see our main contractor proof of insurance guide.
Defining Additional Insured Status
An additional insured is a party other than the named insured who is granted coverage under a policy by endorsement. When a GC requires you to add them as an additional insured on your general liability policy, they are asking to be covered by your policy for claims arising from your work. If you cause an injury on a job site and the injured party sues both you and the GC, your policy defends and potentially indemnifies the GC, not just you.
This is materially different from being listed as a certificate holder. Certificate holder status gives one right: notice of cancellation. Additional insured status gives actual coverage rights under the policy. The two are not the same and a certificate does not automatically grant additional insured status. The endorsement must be added to the underlying policy.
Why Your Clients Demand This Endorsement
General contractors are vicariously liable for the actions of their subcontractors on most commercial projects. If a sub's employee causes a serious injury, the GC will almost certainly be named in the lawsuit regardless of who was actually at fault. Additional insured status on the sub's policy means the GC has a direct source of coverage for those claims rather than relying solely on their own policy. It is a risk transfer mechanism. The GC is pushing the financial exposure back to the party who created the risk, which is the sub doing the work.
Beyond liability, additional insured requirements are often written into the GC's own upstream contract with the owner. The owner requires the GC to be an additional insured on all subs' policies, the GC passes that requirement down the chain, and it becomes a non-negotiable condition of every subcontract. Refusing to provide additional insured status on a commercial project is effectively refusing the job.
Ongoing vs. Completed Operations
This is where most contractors get into trouble. There are two distinct additional insured endorsements that cover different time periods. The CG 20 10 covers ongoing operations, meaning claims that arise while your crew is actively working on the project. The CG 20 37 covers completed operations, meaning claims that arise after the work is done and the project is complete. A defect that shows up two years after a project closes is a completed operations claim.
Many commercial contracts require both the CG 20 10 and the CG 20 37. If your certificate only reflects one of them, the COI will be rejected by any compliance manager who knows what they are looking at. Ask your broker specifically whether both endorsements are on your policy and ensure both form numbers appear on the certificate when required.
Blanket vs. Scheduled Additional Insured Endorsements
A scheduled additional insured endorsement names a specific party. Every time you take a new job with a new GC, your broker adds that GC to the schedule. A blanket additional insured endorsement automatically extends additional insured status to any party you are required to add by written contract, without naming them individually. For contractors working multiple projects with multiple GCs simultaneously, blanket additional insured coverage is significantly more efficient and reduces the chance of a missed endorsement on any one project.
An Illinois mechanical contractor working 12 active commercial projects switched from scheduled to blanket additional insured coverage after a rejection on a project where the endorsement had not yet been added when the certificate was issued. The blanket endorsement costs slightly more in premium but eliminated the administrative lag between signing a contract and having the correct endorsement in place. You can review the endorsement requirements common in Illinois commercial work in our guide to contractor insurance requirements in Illinois.
Does Adding Someone Increase Your Premium?
A blanket additional insured endorsement typically adds between $50 and $300 to your annual premium depending on your carrier, your trade, and your policy size. A scheduled endorsement adding a single named party is often $25 to $100 per party. The premium impact is modest relative to the cost of the projects it enables you to bid.
Where costs escalate is when an owner or GC requires primary and noncontributory language alongside the additional insured endorsement. This language specifies that your policy responds first, before the additional insured's own policy, and your insurer cannot seek contribution from the additional insured's carrier. This shifts more of the financial exposure to your policy and some carriers charge accordingly. If you are seeing unusual premium increases on renewal, check whether primary and noncontributory endorsements were added during the policy period.
PRO-TIP: If you work more than three or four commercial projects per year, ask your broker to add a blanket additional insured endorsement covering both ongoing and completed operations. The annual premium difference versus scheduling each GC individually is typically under $200, and it eliminates the risk of starting a job before the endorsement has been processed.
Contractor Insurance Resources
Additional insured status is one of the most common requirements on contractor certificates of insurance. Clients may also request specific certificate holders or require a waiver of subrogation depending on the contract.
For a full breakdown of how certificates work, see our main main Proof of Insurance for Contractors guide. You can also learn how certificate holders work and when a waiver of subrogation may be required on a COI.
To understand the coverage contractors typically carry, review contractor insurance requirements by state and contractor insurance costs by state.
Insurance requirements and market premiums are subject to change alongside state legislation and carrier appetite. While we audit and update this data annually to ensure reliability (Last Updated: May 2026), these figures are for research and planning purposes only. Always verify specific coverage mandates with your local licensing board or a licensed broker.
Frequently Asked Questions
How many additional insureds can I add to my policy?
With a blanket additional insured endorsement, there is no practical limit. With scheduled endorsements, carriers will add as many named parties as needed, though each may carry a small additional premium. There is no standard cap.
Does additional insured status affect my coverage limits?
The additional insured shares your policy limits, they do not get separate limits. If your policy has a $1 million per-occurrence limit and the additional insured files a claim for $800,000, your remaining per-occurrence limit for other claims in the same period is reduced accordingly. This is why GCs on large projects often require umbrella coverage as well.
Can I be removed as an additional insured?
Yes. Additional insured status can be removed by endorsement at any time. If a sub's policy is cancelled or the endorsement is removed, the additional insured loses coverage rights from that policy. This is why compliance platforms track certificate expiration and require renewal documentation.
What is primary and noncontributory language?
It specifies that the sub's policy is primary, meaning it responds first, and noncontributory, meaning the sub's insurer cannot require the GC's insurer to share in the loss. It protects the GC's own policy from being tapped for claims arising from sub operations. It is increasingly standard language on commercial subcontracts.
Does a homeowner need to be an additional insured?
On residential projects the requirement varies. Some contractors include homeowners as additional insureds as a matter of practice. Others do not unless the homeowner specifically requests it or the contract requires it. On higher-value residential projects it is increasingly common for sophisticated homeowners or their attorneys to request it.