CO-109 denial: claim sent to the wrong payer
The claim went to the wrong payer. This one is a routing problem, not a denial to argue with.
Claim/service not covered by this payer/contractor. You must send the claim/service to the correct payer/contractor.
What the CO group code means
CO — Contractual Obligation
The amount is written off under your contract with the payer. You cannot bill the patient for it.
Is it worth appealing?
Almost never worth appealing. CO-109 means this payer is not the right recipient, so there is nothing for it to reconsider. The work is identifying the correct payer and filing there before its clock runs out.
Why payers issue CO-109
- 01The patient's coverage moved to a different payer or plan.
- 02The member is enrolled in a managed care plan and the claim went to the underlying program.
- 03The claim went to the wrong regional contractor or intermediary.
- 04Intake captured a stale or incorrect insurance card.
What to gather before you appeal
- Current eligibility verification identifying the correct payer.
- The patient's current insurance card.
- The correct payer's filing address or electronic payer ID.
- The original submission date, in case timely filing becomes an issue with the correct payer.
Arguments that work
- This payer is in fact responsible under the member's plan — rare, but worth checking before refiling.
- For the correct payer: the original timely submission to the wrong payer explains the delay.
The deadline
This is the urgent one. The correct payer's timely filing clock has been running the whole time, and it does not pause because you filed elsewhere. Refile immediately and keep proof of the original submission date.
Common questions about CO-109
- Should I appeal a CO-109?
- Usually not. Appealing asks a payer that has no responsibility for the claim to reconsider it. Verify eligibility, find the correct payer, and refile there — speed matters more than argument.
- What if the correct payer says I filed too late?
- Attach proof of the original timely submission to the wrong payer. Many payers will accept that as good cause, especially where the routing error came from incorrect information on the card.
Draft the CO-109 appeal in about three minutes
Upload the denial. Undeny reads it, drafts a payer-specific appeal letter citing this code and the record, and tracks the deadline until the money comes back.
Other denial codes
- CO-197CO-197 denial: prior authorization absent
- CO-16CO-16 denial: claim lacks information
- CO-29CO-29 denial: timely filing limit expired
- CO-45CO-45: charge exceeds fee schedule
- CO-50CO-50 denial: not deemed medically necessary
- CO-97CO-97 denial: service already included in another payment
- CO-18CO-18 denial: exact duplicate claim
- CO-22CO-22 denial: another payer is primary
- CO-27CO-27 denial: coverage terminated before the service
- CO-96CO-96 denial: non-covered charges
- CO-151CO-151 denial: too many services billed
- CO-B7CO-B7 denial: provider not eligible on the date of service
- CO-4CO-4 denial: modifier inconsistent or missing
- CO-11CO-11 denial: diagnosis inconsistent with the procedure
- PR-1PR-1: deductible amount — and why it is not a denial
- PR-204PR-204: not covered under the patient's benefit plan