What does this denial code mean?
Type the code from the remittance (CO-16, PR-1, N4, MA130) or a few words (timely filing, authorization, bundled). You get the official X12 text, a plain-English translation, the usual causes, the fix, and whether to appeal or send a corrected claim.
Every one of the 407 claim adjustment reason codes and 1,137 remark codes is here with its official text. 116 of the most common ones are translated into plain English with the fix.
Check the code on the remittance: adjustment reason codes are a number (16) or a letter and number (B7), often shown with a group such as CO or PR; remark codes start with N, M or MA. Try a word from the denial text instead.
Common combinations
A reason code says what happened; the remark code next to it says why. These pairs show up on almost every practice's remittance. Click one to translate both.
Group, reason, remark
Every adjustment on an electronic remittance (the 835) has three parts. Knowing which part you are looking at decides what to do next.
Group codes: who owes the difference
The provider owes the difference. The patient cannot be billed for this amount.
The patient owes this amount (deductible, coinsurance, copay or a non-covered service the patient agreed to pay for).
Neither the provider nor the patient is being told to pay. Used when no other group fits, for example when another payer should pay.
The payer reduced the payment for a reason other than the contract, usually with the right to appeal.
What to do with each answer
Fix the field and resend the same claim with frequency code 7 and the original claim number. Not an appeal.
Write to the payer with records and a reason. Used when the claim was right and the decision was wrong.
Depends on the cause: incomplete coding gets a corrected claim; a wrong payer decision gets an appeal.
Nothing wrong with the claim: the patient (or a secondary payer) owes this part.
The claim belongs to another payer, or the payer needs something only the patient or a phone call can give.
Informational or contractual. Post it and move on.
One rule that saves the most money: a corrected claim does not stop the timely filing clock, and an appeal has its own window (Medicare: 120 days from the remittance date; most commercial contracts 60 to 180 days). Work denials the week they arrive. Revelrex denial management does exactly that for practices that would rather not.
Every code we explain, A to Z
Each one has its own page with the plain-English meaning, causes, fix and deadline. The search box above also returns the official text for every other active code.
Claim adjustment reason codes (CARC)
- PR-1Deductible
- PR-2Coinsurance
- PR-3Copayment
- CO-4Procedure code does not match the modifier
- CO-5Procedure code does not match the place of service
- CO-6Procedure code does not match the patient's age
- CO-7Procedure code does not match the patient's gender
- CO-8Procedure not allowed for this provider type or specialty
- CO-9Diagnosis does not match the patient's age
- CO-11Diagnosis does not support the procedure
- CO-15Authorization number missing, invalid or does not apply
- CO-16Claim is missing information or has a billing error
- OA-18Exact duplicate claim
- CO-19Work-related injury: bill workers' compensation
- CO-22Another payer may be primary
- OA-23Prior payer's payment and adjustments applied
- CO-24Covered under a capitation or managed care plan
- PR-26Service before coverage began
- PR-27Service after coverage ended
- CO-29Timely filing limit expired
- CO-31Patient cannot be identified as insured
- PR-35Lifetime benefit maximum reached
- CO-39Services denied when authorization was requested
- CO-45Charge exceeds the fee schedule or contracted rate
- CO-49Routine or preventive exam not covered
- CO-50Not medically necessary
- PR-51Pre-existing condition
- CO-55Experimental or investigational
- CO-58Wrong place of service for this treatment
- CO-59Multiple or concurrent procedure rules applied
- CO-96Non-covered charge
- CO-97Included in the payment for another service (bundled)
- CO-107Related or qualifying service not on the claim
- CO-109Wrong payer or contractor
- PR-119Benefit maximum for this period reached
- CO-140Patient ID and name do not match
- CO-146Diagnosis invalid for the date of service
- CO-150Documentation does not support this level of service
- CO-151Documentation does not support this many services
- CO-167Diagnosis not covered
- CO-170Not paid when billed by this type of provider
- CO-181Procedure code invalid on the date of service
- CO-182Modifier invalid on the date of service
- CO-183Referring provider not eligible to refer
- CO-185Rendering provider not eligible to perform this service
- CO-197No prior authorization
- CO-198Authorization exceeded
- PR-204Not covered under the patient's current benefit plan
- CO-206NPI missing
- CO-208NPI not matched
- CO-226Information requested from the provider not received
- CO-227Information requested from the patient not received
- CO-231Mutually exclusive procedures
- CO-234Procedure not paid separately
- CO-242Services not from a network or primary care provider
- CO-243Services not authorized by network or primary care provider
- CO-252Attachment or documentation required
- CO-253Sequestration reduction
- CO-276Denied by the prior payer, so not covered here
- CO-284Authorization does not apply to the billed services
- CO-288Referral absent
- CO-A1Claim denied, see remark code
- CO-B7Provider not certified or eligible to be paid for this service
- CO-B9Patient is enrolled in hospice
- CO-B13Previously paid
- CO-B15Requires a qualifying service that was not received or covered
- CO-B16New patient qualifications not met
- CO-B20Service partly or fully furnished by another provider
Remittance advice remark codes (RARC)
- M15Bundled: components of the same procedure
- M20HCPCS code missing or invalid
- M51Procedure code missing or invalid
- M53Days or units missing or invalid
- M76Diagnosis missing or invalid
- M77Place of service missing or invalid
- M79Charge missing or invalid
- M80Not covered in the same session as a service already processed
- M81Code to the highest level of specificity
- M86Already paid for the same or similar service in this period
- M119National Drug Code missing or invalid
- M127Medical record missing
- M144Pre- or post-operative care is in the surgery payment
- MA04Primary payer information missing on a secondary claim
- MA27Medicare number or name wrong
- MA61Social Security number missing or invalid
- MA63Principal diagnosis missing or invalid
- MA92Other insurance information missing
- MA130Unprocessable claim, no appeal rights
- N4Primary insurance EOB missing or invalid
- N19Incidental to the primary procedure
- N20Not payable with another service on the same date
- N30Patient not eligible for this service
- N54Claim does not match the authorization
- N56Procedure code not valid for the service or the date
- N95This provider type or specialty may not bill this service
- N115Decision based on a Local Coverage Determination
- N130See plan benefit documents for restrictions
- N179Information requested from the patient
- N180Does not meet the criteria for the category billed
- N185Do not resubmit this claim
- N197Subscriber must update insurance information
- N198Rendering provider must be affiliated with the pay-to provider
- N265Ordering provider identifier missing or invalid
- N286Referring provider identifier missing or invalid
- N290Rendering provider identifier missing or invalid
- N362Units exceed the acceptable maximum
- N382Patient identifier missing or invalid
- N386Decision based on a National Coverage Determination
- N418Misrouted claim
- N428Not covered in this place of service
- N519Invalid combination of modifiers
- N522Duplicate of a crossover claim
- N525Within the global period of another service
- N569Not covered for the reported diagnosis
- N657Bill with the appropriate code for these services
- N661Documentation does not support medical necessity
- N706Documentation missing
Code lists and official descriptions: X12 Claim Adjustment Reason Codes and Remittance Advice Remark Codes, as published at x12.org. The plain-English guidance is Revelrex's and is general: payer contracts and state rules decide the exact deadline for any one claim.
Tired of translating denials one at a time?
Send one month of de-identified denials and a Revelrex analyst groups them by reason, payer and dollars, then walks you through what was never reworked. Free, no obligation.