Most denied claims are not lost money. They are claims with a fixable problem, and the denial code on the remittance tells you what the problem is. This guide covers the denials practices see most often, what usually causes them and the quickest way to fix each one, with a link to our full explanation of every code.
How to Read a Denial
Each denied line on an electronic remittance carries three pieces of information:
- A group code that says who is responsible: CO (contractual obligation, usually not billable to the patient), PR (patient responsibility), OA (other adjustment) or PI (payer initiated).
- A claim adjustment reason code (CARC), a number that says why the claim was adjusted or denied.
- Often a remark code (RARC), such as N290 or M76, that gives the specific detail. When a denial is unclear, the remark code is usually where the answer is.
The Denials Practices See Most
| Code | What it means | Usual fix |
|---|---|---|
| CARC 16 | Missing information or a billing error | Read the remark code, fix the field, send a corrected claim |
| CARC 197 | Prior authorization missing | Find or request the authorization, add the number, resubmit or appeal |
| CARC 50 | Not medically necessary | Check the payer’s coverage policy and diagnosis codes, appeal with notes |
| CARC 97 | Bundled into another service | Check NCCI edits, add a modifier only if the services were truly separate |
| CARC 4 | Modifier missing or wrong | Correct the modifier and send a corrected claim |
| CARC 18 | Duplicate claim | Check claim history before resubmitting; use the corrected-claim process |
| CARC 22 | Another payer may be primary | Update coordination of benefits, bill the primary payer first |
| CARC 27 | Coverage ended before the service | Verify eligibility, bill the current plan or the patient |
| CARC 31 | Patient not identified as a member | Check the member ID, name and date of birth, resubmit |
| CARC 29 | Filing limit expired | Appeal only with proof of timely submission |
Where Most Denials Start
Denials tend to come from the same few places. Fixing the source prevents the next hundred.
- Registration and eligibility: wrong member ID, old insurance, coordination of benefits not updated. These drive CARC 22, 27 and 31.
- Authorizations: not requested, or obtained for a different code or date. These drive CARC 197.
- Coding and documentation: missing modifiers, bundled services, diagnosis codes that do not support the service. These drive CARC 4, 50 and 97.
- Claim data: missing NPI, taxonomy or other required fields. These drive CARC 16.
A Simple Weekly Denial Routine
- Pull every denial from the last week and sort by dollar amount.
- Group them by denial code and by payer.
- Work the highest dollar amounts first, and anything close to its filing or appeal deadline.
- For each group, ask where the problem started: front desk, authorization, coding or claim data.
- Fix that step, not just the claim.
When to Appeal and When to Correct
If the claim had wrong or missing information, send a corrected claim: payers do not expect an appeal for a data error. Appeal when the claim was right and the payer was wrong, and include the documentation and the payer’s own policy that supports you. Do not appeal a correct contractual adjustment or a true duplicate.
Corrected Claim or Appeal
Send a corrected claim when
- A field was missing or wrong
- A modifier was missing or wrong
- The member ID or payer order was wrong
Appeal when
- The claim was right as submitted
- The notes support medical necessity
- You can prove the claim was filed on time
When Denials Keep Coming Back
If the same denials repeat month after month, the problem is a process, not a claim. A billing audit can find the source, and a billing company with experience in your specialty can take denial work off your team. You can compare medical billing companies or browse all denial codes we explain.
