What better way to get going in 2007 than to analyze why our
claims are getting denied by Medicare? The No. 1 denial reason in
2006 was the annoying CO18 (duplicate claim) denial.
One reason for a CO18 denial is that the claim was paid but was
rebilled to Medicare before the payment was received or posted.
However, this is the best-case scenario and usually is not the main
reason for the denial. Another reason is caused by billing for the
same HCPC and date of service for different brands. This often
happens with wound care, for example, because vendors could make
similar items that use the same HCPC. Providers often make the
mistake of billing them separately — one line item with three
units from the first manufacturer and another line item with five
units from the second — instead of combining them.
However, the main cause for the CO18 is that the claim was
billed and denied, then resubmitted with the biller's paying
attention to the correction that needed to be made based on the
When you receive a CO18 denial, research the claim for previous
submissions and find the original denial. Then you must fix the
claim and resubmit with the corrected information or appeal the
original decision with additional information from the patient
chart. If you can't find the original denial on the EOB or ERA,
contact Medicare by calling the Voice Response Unit or using Claim
Never simply resubmit a CO18 because it will just get denied
again with another CO18, and you will be stuck in a vicious
— Sarah Hanna
Based on analysis of claims adjudicated by the Medicare
contractors between July 1, 2006, and Sept. 30, 2006, and processed
for RemitDATA customers. Source: RemitDATA, 866/885-2974,
Sarah Hanna is a reimbursement consultant and vice president of
ECS Billing & Consulting, Tiffin, Ohio, and specializes in
proper billing protocols, Medicare coverage guidelines and billing
office procedures. She can be contacted at 419/448-5332 or email@example.com.