CARC 18OA · Other Adjustment
This claim or service line is an exact duplicate of one already submitted and processed.
- Common causes
- The same claim was submitted twice, often due to a billing system resubmission glitch or a corrected claim sent without the proper resubmission coding.
- Suggested fix
- Confirm whether this is truly a duplicate; if it's a correction to a prior claim, resubmit using the appropriate corrected-claim frequency code instead of a fresh submission.
Related Other Adjustment codes
109This payer isn't responsible for this claim; it needs to be sent to a different payer or contractor.136The claim wasn't processed correctly because it didn't follow the rules or requirements set by a prior (primary) payer.140The member ID number submitted doesn't match the patient or subscriber name on file with the payer.19The payer has determined this claim relates to a work injury or illness, making workers' compensation the responsible party instead.215Payment was adjusted based on a third-party settlement where the payer has subrogation rights to recover costs.22The payer believes another insurance plan should be billed first or is otherwise responsible under coordination-of-benefits rules.23This adjustment reflects how a prior payer already processed the claim, reducing what this payer pays as a result.253Payment was reduced due to mandatory federal budget sequestration, a government-wide across-the-board cut applied to Medicare payments.
Frequently asked questions
What does CARC 18 mean?
This claim or service line is an exact duplicate of one already submitted and processed.
How do I resolve CARC 18?
Confirm whether this is truly a duplicate; if it's a correction to a prior claim, resubmit using the appropriate corrected-claim frequency code instead of a fresh submission.
Why does CARC 18 happen?
The same claim was submitted twice, often due to a billing system resubmission glitch or a corrected claim sent without the proper resubmission coding.
CARC codes maintained by X12 (x12.org). Descriptions on this site are original reference interpretations. Always verify codes with authoritative sources before making billing decisions.