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Denial code CO-109: what it means and what to do

Denial code CO-109 on your Explanation of Benefits: The claim was sent to the wrong insurer.

What CO-109 means

The claim was sent to the wrong insurer.

CO means contractual obligation: under its contract, the provider is usually responsible for this amount, so an in-network provider generally should not bill you for it.

What to do

Call the plan to confirm which insurance is primary, update your information, and ask to reprocess the claim.

Your deadline

Most plans give you 180 days from the denial notice to file an internal appeal. Original Medicare gives 120 days from the Medicare Summary Notice, and Medicare Advantage plans 65 days from their decision. Check the date printed on your letter.

More on this reason: Other insurance (coordination of benefits).

Other denial codes

• CO-50
• CO-197
• CO-198
• CO-15
• CO-16
• CO-18
• CO-97
• CO-4
• CO-11
• CO-29
• CO-96
• CO-204
• CO-119
• CO-167
• CO-55
• CO-242
• CO-22
• CO-27
• CO-26
• CO-31
• CO-45
• PR-1
• PR-2
• PR-3

Sources

1. HealthCare.gov: Internal appeals
2. 29 CFR 2560.503-1, claims procedure for employer health plans