Legal & Risk Transfer
Primary and Non-Contributory vs. Excess: The Difference in a Loss
Two policies cover the same accident. Which one pays first, and whether the first one can bill the second, decides whose retention and loss history absorb the claim. Here is how the Other Insurance condition settles it.
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Two policies, one loss
A crew from Summit Steel Erectors loses control of a beam during a pick, and a delivery driver on site is injured. The driver sues the general contractor and Summit. The general contractor is an additional insured on Summit's CGL. It also has its own CGL, with a $100,000 self-insured retention. Both policies arguably cover the general contractor for the same claim.
Which one pays first, and whether the first one can make the second one share, is decided by each policy's Other Insurance condition and the endorsements that modify it. That answer determines whose retention gets spent, whose limits get eroded and whose loss runs show the claim at the next renewal.
What the standard Other Insurance condition says
In the ISO CGL coverage form, CG 00 01, Section IV, Condition 4, the policy is primary unless one of its excess provisions applies. One of those provisions makes the policy excess over any other primary insurance available to the named insured covering liability for premises or operations, or products and completed operations, for which the named insured has been added as an additional insured.
Read from the general contractor's side, that is helpful. The general contractor's own CGL steps back and lets the subcontractor's policy respond first for claims within the additional insured grant. When two policies are both primary, the condition sets the method of sharing: equal shares if every policy allows it, otherwise in proportion to each policy's limits.
The same condition lists other coverage the CGL sits behind, such as builder's risk or installation coverage for your work and property insurance on premises rented to you. Those provisions rarely decide a bodily injury claim. The additional insured provision almost always does.
Where the default breaks down
The default only works if the subcontractor's policy accepts the primary role. Many carrier additional insured endorsements and manuscript forms say the reverse: coverage for an additional insured is excess over any other valid and collectible insurance available to the additional insured, unless a written contract requires it to be primary.
Now both policies claim to be excess. Courts faced with competing excess clauses often treat them as cancelling each other out and order the carriers to share. The general contractor's carrier contributes, the retention is spent and the loss lands on the general contractor's loss history, even though the contract required the subcontractor to carry the risk.
A related problem appears when the subcontractor's carrier pays first and then seeks contribution from the general contractor's carrier. Without non-contributory wording, nothing in the policy stops that.
The general contractor rarely sees this coming, because the certificate looks the same either way. The excess wording sits in the carrier's additional insured endorsement or in a separate other insurance amendment, and only the forms schedule shows it.
What CG 20 01 changes
ISO introduced CG 20 01, Primary and Noncontributory, Other Insurance Condition, with its 04 13 filings. It adds to the Other Insurance condition a statement that the policy is primary to, and will not seek contribution from, any other insurance available to an additional insured, provided two conditions are met: the additional insured is a Named Insured on that other insurance, and the named insured agreed in a written contract or agreement that its insurance would be primary and would not seek contribution.
The two words do different jobs. Primary means the subcontractor's policy pays first. Non-contributory means it cannot turn around and bill your own policy for a share.
Both conditions deserve a close read. The protection applies to policies on which you are a Named Insured, which is exactly what you want to protect: your own CGL and umbrella. And the written agreement must exist before the loss and must actually require primary and non-contributory coverage. In Pikorua Security's 2026 benchmark, primary and non-contributory wording was absent in 37% of deficient certificate packets.
Owners should also check how far down the chain the promise reaches. When an owner is an additional insured on a lower-tier subcontractor's policy through blanket wording such as CG 20 38, whether the primary and non-contributory protection extends to the owner depends on the written contracts at each tier and on the endorsement wording. Ask counsel to confirm the flow-down language in every tier of contract, not just the prime contract.
Do not stop at the primary layer
A serious injury claim will reach the umbrella. If the contract is silent about excess layers, the subcontractor's umbrella carrier may argue that its policy sits excess over every other policy available to the general contractor, including the general contractor's own primary and umbrella. Courts differ on whether an additional insured's own coverage has to be exhausted before a subcontractor's umbrella responds.
Effective exhibits require the subcontractor's umbrella or excess policy to include the additional insured on a follow form basis and to apply on a primary and non-contributory basis to the additional insured's own primary and excess insurance. That wording belongs in the contract, drafted with counsel, and then in the umbrella endorsement itself.
How to check it on a certificate packet
A remark in the description box that says "primary and noncontributory where required by written contract" is a summary, not coverage. Pikorua Security's Endorsement Validator reads the endorsement text rather than the certificate remark and compares it to the contract exhibit rule, so a missing CG 20 01 surfaces as a specific deficiency the broker can fix.
Whether you review by hand or with software, confirm five things:
- CG 20 01, or equivalent primary and non-contributory language, is attached as an endorsement.
- A signed contract requires primary and non-contributory coverage in writing, and the contracting entity matches the Named Insured.
- The carrier's additional insured endorsement does not make additional insured coverage excess by default.
- The umbrella's other insurance wording and its schedule of underlying coverage match the contract.
- Edition dates are current on every form. CG 20 01 exists only from the 04 13 edition onward.
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About the author
Ananya Rao
Co-founder & CEO, Pikorua Security
Ananya co-founded Pikorua Security after working as a construction risk manager for a US ENR Top 100 general contractor, where she reviewed subcontractor insurance packets and tender files firsthand. She studied civil engineering at IIT Madras.
The Risk Transfer Brief explains insurance and contract concepts in general terms. Pikorua Security is software, not a law firm, insurer or broker. For contract drafting, or a coverage position on a specific claim, work with your coverage counsel.