Denial Code List
Every adjustment code and remark code we cover, what each means, and whether it is worth appealing. 69 adjustment pages across 54 codes, plus 22 remark codes, written the way a billing manager would explain them.
These pages change when the codes do. If your team wants the adjustment codes on one sheet, with a verdict and next step for each, get the Denial Code Appeal Playbook (dated, so you know when it was current).
Most Searched
The codes billers look up most, by measured search volume.
CO 97 · CO 96 · OA 23 · PR 204 · CO 109 · CO 197 · CO 45 · CO 50
Looking up a procedure or device, not a code? See our commercial payer coverage references for CPT 27278 (SI joint fusion), E0483 (HFCWO vest) and E0738 (upper-limb rehab), with the policy, stance and source on every row.
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Remark Codes
An adjustment code says a claim was reduced. A remark code says why. You need both.
N130
The member's plan restricts this service, and the payer has pointed you at the benefit document instead of naming the restriction.
Read the N130 pageN115
The decision came from a Local Coverage Determination, the regional Medicare policy that says when this service is covered.
Read the N115 pageN30
The patient was not eligible for this particular service on that date. That is narrower than not being covered at all, and the difference matters.
Read the N30 pageMA04
This was billed as a secondary claim and the payer has no record of what the primary did with it.
Read the MA04 pageM80
Another service billed for the same patient on the same day already absorbed this one.
Read the M80 pageN56
The procedure code does not match what was done, or was not valid on that date of service.
Read the N56 pageN59
The payer has pointed you at the provider manual rather than naming the rule it applied.
Read the N59 pageN822
A modifier the payer needed was missing from the procedure.
Read the N822 pageN362
More days or units were billed than the payer will accept for that code.
Read the N362 pageN290
The rendering provider identifier is missing, incomplete or wrong.
Read the N290 pageN381
The payer is pointing at your contract rather than naming the rule it applied.
Read the N381 pageMA130
The claim was unprocessable, so it was never adjudicated and carries no appeal rights at all.
Read the MA130 pageN211
The payer is telling you this particular decision carries no appeal rights.
Read the N211 pageN19
The payer treats this procedure as incidental to the main one, so it pays nothing on its own.
Read the N19 pageM15
Services billed separately were bundled, because the payer considers them components of one procedure.
Read the M15 pageM51
A procedure code is missing, incomplete or not valid.
Read the M51 pageN522
This duplicates a claim that is already crossing over from another payer.
Read the N522 pageN706
The payer says a document it needed never arrived.
Read the N706 pageN180
The payer says what you billed does not qualify for the billing category you put it under.
Read the N180 pageMA63
The principal diagnosis is missing, not coded to full specificity, or not valid on the date of service.
Read the MA63 pageN517
The payer is asking for a new claim that includes the information it requested.
Read the N517 pageN265
The NPI of the provider who ordered the service is missing, incomplete or wrong.
Read the N265 page
Contractual and Patient Responsibility
PR 1
Applied to the patient deductible.
Read the PR 1 pagePR 2
Applied to patient coinsurance.
Read the PR 2 pagePR 3
Applied to the patient co-payment.
Read the PR 3 pageCO 45
Charge is above the contracted rate. The difference is written off.
Read the CO 45 pageCO 131
A negotiated discount specific to this claim was applied.
Read the CO 131 pageCO 253
A flat federal sequestration reduction was applied.
Read the CO 253 pageCO 144
The payer applied an incentive adjustment under a program or contract term, for example one tied to a preferred product or service.
Read the CO 144 pageCO 132
The payment was adjusted under the terms of a demonstration project the provider agreed to in advance.
Read the CO 132 page
Prior Authorisation
CO 197
The payer says no prior authorisation was on file.
Read the CO 197 pagePR 197
The payer says no prior authorisation was on file.
Read the PR 197 pageCO 198
Authorised, but more units or visits were billed than approved.
Read the CO 198 pageCO 15
The authorisation number is missing, invalid, or does not match.
Read the CO 15 page
Missing Information
CO 16
Something the payer needed was missing or wrong on the claim.
Read the CO 16 pagePR 16
Something the payer needed was missing or wrong on the claim.
Read the PR 16 pageCO 125
The submission itself had an error.
Read the CO 125 pageCO 252
The payer wants supporting documentation attached.
Read the CO 252 pageCO 226
The payer asked you for information and did not get it, or did not get enough.
Read the CO 226 page
Coding
CO 5
The procedure does not match the place of service billed.
Read the CO 5 pageCO 4
The procedure code and the modifier do not agree.
Read the CO 4 pageCO 11
The diagnosis does not match the procedure billed.
Read the CO 11 pageCO 59
Reduced under multiple-procedure rules.
Read the CO 59 pageCO 150
The payer says the records do not support the level of service billed.
Read the CO 150 pageCO 8
The procedure does not match the provider type or specialty on file.
Read the CO 8 pageCO 6
The procedure does not fit the patient's age.
Read the CO 6 pageCO 181
The procedure code was not valid on that date of service.
Read the CO 181 pageCO 146
The diagnosis was not valid on that date of service.
Read the CO 146 page
Medical Necessity
CO 58
The payer decided the service should not have been done where it was done.
Read the CO 58 pageCO 50
The payer decided the service was not medically necessary.
Read the CO 50 pagePR 50
The payer decided the service was not medically necessary.
Read the PR 50 pageCO 167
The diagnosis billed is not covered for this service.
Read the CO 167 pagePR 167
The diagnosis billed is not covered for this service.
Read the PR 167 pageCO 55
Treated as experimental or investigational.
Read the CO 55 pagePR 55
Treated as experimental or investigational.
Read the PR 55 page
Eligibility
CO 185
The rendering provider is not eligible to perform the service billed.
Read the CO 185 pageCO 242
The provider was out of network, or not the patient's assigned primary care provider.
Read the CO 242 pagePR 242
The provider was out of network, or not the patient's assigned primary care provider.
Read the PR 242 pagePR 27
Coverage had ended on the date of service.
Read the PR 27 pageCO 27
Coverage had ended on the date of service.
Read the CO 27 pagePR 26
Service fell before coverage started.
Read the PR 26 pageCO 26
Service fell before coverage started.
Read the CO 26 pageCO B7
The provider was not certified or eligible for this service on that date.
Read the CO B7 pageCO 24
The patient is in a capitated or managed-care plan, so this is paid under that contract.
Read the CO 24 pageCO 31
The payer cannot find this patient as a member.
Read the CO 31 pageCO 170
This payer does not pay this service when this type of provider performs it.
Read the CO 170 page
Bundling and NCCI
CO 236
This procedure and another one billed the same day cannot be billed together under NCCI.
Read the CO 236 pageCO 97
The payer says this is already paid inside another service.
Read the CO 97 pageCO 234
This procedure is not paid separately.
Read the CO 234 pageCO B15
A required prior service was not billed or not covered.
Read the CO B15 pageCO 107
The related service this one depends on was not on the claim.
Read the CO 107 page
Timely Filing
Units and Frequency
Benefit Maximums
Coordination of Benefits
OA 22
Another plan should pay first.
Read the OA 22 pageCO 22
Another plan should pay first.
Read the CO 22 pageOA 109
Wrong payer or wrong contractor for this claim.
Read the OA 109 pageCO 109
Wrong payer or wrong contractor for this claim.
Read the CO 109 pageOA 23
A prior payer already adjusted this, and that adjustment carries over.
Read the OA 23 pageCO 23
A prior payer already adjusted this, and that adjustment carries over.
Read the CO 23 pageCO 21
The payer says a no-fault insurer, most often an auto policy, is liable for this injury.
Read the CO 21 page
Duplicates
Non-Covered
PR 96
Not a covered charge under this plan.
Read the PR 96 pageCO 96
Not a covered charge under this plan.
Read the CO 96 pagePR 204
Not covered under the patient’s current benefit plan.
Read the PR 204 pageCO 204
Not covered under the patient’s current benefit plan.
Read the CO 204 pagePR 49
Treated as a routine or preventive service the plan does not cover.
Read the PR 49 page
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