Denial Codes in Medical Billing Codes

Medical billing denial codes are specific indicators used by insurance companies to explain why a healthcare claim has been rejected or denied. These codes are essential in the revenue cycle management process, as they provide detailed reasons for denials, such as missing or incorrect patient information, improper coding, lack of medical necessity, or failure to obtain prior authorization. Each denial code highlights a unique issue, allowing healthcare providers to understand the specific reason for the denial and take corrective action to resolve the claim.

Addressing denial codes promptly and accurately is vital for healthcare providers to avoid revenue loss and delays in payment. By analyzing denial trends and identifying common causes, practices can improve their billing processes, reduce claim rejections, and ensure faster reimbursement. Efficient management of medical billing denial codes helps maintain a healthy revenue cycle and minimizes disruptions to cash flow in the healthcare setting

Below is the list of the denial codes:

CARC Code	Description	RARC Code	Description
CO-3	Co-payment Amount
CO-4	The procedure code is inconsistent with the modifier used.	N519	Invalid combination of HCPCS modifiers.
CO-4	The procedure code is inconsistent with the modifier used.	N572	This procedure is not payable unless appropriate nonpayable reporting codes and associated modifiers are submitted.
CO-5	The procedure code/type of bill is inconsistent with the place of service.	M77	Missing/incomplete/invalid/inappropriate place of service.
CO-6	The procedure/revenue code is inconsistent with the patient's age	N129	Not eligible due to the patient's age.
CO-8	The procedure code is inconsistent with the provider type/specialty (taxonomy).	N95	This provider type/provider specialty may not bill this service.
CO-9	The diagnosis is inconsistent with the patient's age.	N129	Not eligible due to the patient's age.
CO-11	The diagnosis is inconsistent with the procedure.	N657	This should be billed with the appropriate code for these services.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	M20	Missing/incomplete/invalid HCPCS.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	M22	Missing/incomplete/invalid number of miles traveled.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	M50	Missing/incomplete/invalid revenue code(s)
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	M51	Missing/incomplete/invalid procedure code(s).
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	M53	Missing/incomplete/invalid days or units of service.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	M62	Missing/incomplete/invalid treatment authorization code.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	M67	Missing/incomplete/invalid other procedure code(s).
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	M76	Missing/incomplete/invalid diagnosis or condition
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	M77	Missing/incomplete/invalid/inappropriate place of service.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	M119	Missing/incomplete/invalid/deactivated/withdrawn National Drug Code (NDC).
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	M123	Missing/incomplete/invalid name, strength, or dosage of the drug furnished.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	MA04	Secondary payment cannot be considered without the identity of or payment information from the primary payer. The information was either not reported or was illegible.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	MA31	Missing/incomplete/invalid beginning and ending dates of the period billed.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	MA32	Missing/incomplete/invalid number of covered days during the billing period.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	MA39	Missing/incomplete/invalid gender.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	MA40	Missing/incomplete/invalid admission date.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	MA41	Missing/incomplete/invalid admission type.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	MA42	Missing/incomplete/invalid admission source
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation	MA63	Missing/incomplete/invalid principal diagnosis.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	MA65	Missing/incomplete/invalid admitting diagnosis
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	MA66	Missing/incomplete/invalid principal procedure code.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	MA120	Missing/incomplete/invalid CLIA certification number
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation	N34	Incorrect claim form/format for this service.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N37	Missing/incomplete/invalid tooth number/letter.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N39	Procedure code is not compatible with tooth number/letter
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N46	Missing/incomplete/invalid admission hour.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N50	Missing/incomplete/invalid discharge information.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation	N54	Claim information is inconsistent with precertified/authorized services.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N54	Claim information is inconsistent with precertified/authorized services.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N56	Procedure code billed is not correct/valid for the services billed or the date of service billed.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N62	Dates of service span multiple rate periods. Resubmit separate claims.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N63	Rebill services on separate claim lines.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N75	Missing/incomplete/invalid tooth surface information.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N208	Missing/incomplete/invalid DRG code.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N251	Missing/incomplete/invalid attending provider taxonomy.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation	N253	Missing/incomplete/invalid attending provider primary identifier.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N257	Missing/incomplete/invalid billing provider/ supplier primary identifier.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N261	Missing/incomplete/invalid operating provider name.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation	N265	Missing/incomplete/invalid ordering provider primary identifier.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N286	Missing/incomplete/invalid referring provider primary identifier.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N290	Missing/incomplete/invalid rendering provider primary identifier
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N305	Missing/incomplete/invalid injury/accident date
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N308	Missing/incomplete/invalid appliance placement date.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N317	Missing/incomplete/invalid discharge hour.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N318	Missing/incomplete/invalid discharge or end of care date.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N329	Missing/incomplete/invalid patient birth date.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N330	Missing/incomplete/invalid patient death date.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N341	Missing/incomplete/invalid surgery date.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N346	Missing/incomplete/invalid oral cavity designation code.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N382	Missing/incomplete/invalid patient identifier.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N434	Missing/Incomplete/Invalid Present on Admission indicator.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N480	Incomplete/invalid Explanation of Benefits (Coordination of Benefits or Medicare Secondary Payer).
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N519	Invalid combination of HCPCS modifiers
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N572	This procedure is not payable unless appropriate nonpayable reporting codes and associated modifiers are submitted.
CO-16	Claim/service lacks information or has submission/billing error(s). Do not use this code for claims attachment(s)/other documentation.	N823	Incomplete/Invalid procedure modifier(s).
CO-18	Exact duplicate claim/service.
CO-18	Exact duplicate claim/service.	N522	Duplicate of a claim processed, or to be processed, as a crossover claim.
CO-18	Exact duplicate claim/service.	N702	Decision based on review of previously adjudicated claims or for claims in process for the same/similar type of services.
CO-22	This care may be covered by another payer per coordination of benefits.
CO-22	This care may be covered by another payer per coordination of benefits.	MA92	Missing plan information for other insurance.
CO-22	This care may be covered by another payer per coordination of benefits.	N36	Claim must meet primary payer's processing requirements before we can consider payment.
CO-22	This care may be covered by another payer per coordination of benefits.	N479	Missing Explanation of Benefits (Coordination of Benefits or Medicare Secondary Payer).
CO-26	Expenses incurred prior to coverage.	N30	Patient ineligible for this service.
CO-29	The time limit for filing has expired.
CO-35	Lifetime benefit maximum has been reached.	N117	This service is paid only once in a patient's lifetime.
CO-50	These are non-covered services because this is not deemed a 'medical necessity' by the payer.	N10	Adjustment based on the findings of a review organization/professional consult/manual adjudication/medical advisor/dental advisor/peer review
CO-50	These are non-covered services because this is not deemed a 'medical necessity' by the payer.	N130	Consult plan benefit documents/guidelines for information about restrictions for this service.
CO-54	Multiple physicians/assistants are not covered in this case.	N646	Reimbursement has been adjusted based on the guidelines for an assistant.
CO-58	Treatment was deemed by the payer to have been rendered in an inappropriate or invalid place of service.	N760	This facility is not authorized to receive payment for the service(s).
CO-60	Charges for outpatient services are not covered when performed within a period of time prior to or after inpatient services.
CO-60	Charges for outpatient services not covered when performed within a period of time prior to or after inpatient services.	N130	Consult plan benefit documents/guidelines for information about restrictions for this service.
CO-95	Plan procedures not followed.	N182	This claim/service must be billed according to the schedule for this plan.
CO-96	Non-covered charge(s).	M2	Not paid separately when the patient is an inpatient.
CO-96	Non-covered charge(s).	M80	Not covered when performed during the same session/date as a previously processed service for the patient.
CO-96	Non-covered charge(s).	N10	Adjustment based on the findings of a review organization/professional consult/manual adjudication/medical advisor/dental advisor/peer review.
CO-96	Non-covered charge(s).	N30	Patient ineligible for this service.
CO-96	Non-covered charge(s).	N39	Procedure code is not compatible with tooth number/letter.
CO-96	Non-covered charge(s).	N54	Claim information is inconsistent with precertified/authorized services.
CO-96	Non-covered charge(s).	N129	Not eligible due to the patient's age.
CO-96	Non-covered charge(s).	N161	This drug/service/supply is covered only when the associated service is covered.
CO-96	Non-covered charge(s).	N198	Rendering provider must be affiliated with the pay-to provider.
CO-96	Non-covered charge(s).	N216	We do not offer coverage for this type of service or the patient is not enrolled in this portion of our benefit package.
CO-96	Non-covered charge(s).	N424	Patient does not reside in the geographic area required for this type of payment.
CO-96	Non-covered charge(s).	N431	Not covered with this procedure.
CO-96	Non-covered charge(s).	N569	Not covered when performed for the reported diagnosis.
CO-96	Non-covered charge(s).	N643	The services billed are considered Not Covered or NonCovered (NC) in the applicable state fee schedule.
CO-97	The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.	M2	Not paid separately when the patient is an inpatient.
CO-97	The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.	M15	Separately billed services/tests have been bundled as they are considered components of the same procedure. Separate payment is not allowed.
CO-97	The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.	M80	Not covered when performed during the same session/date as a previously processed service for the patient
CO-97	The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.	M86	Service denied because payment already made for same/similar procedure within set time frame.
CO-97	The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.	M97	Not paid to practitioner when provided to patient in this place of service. Payment included in the reimbursement issued the facility.
CO-97	The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.	N19	Procedure code incidental to primary procedure.
CO-97	The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.	N20	Service not payable with other service rendered on the same date.
CO-97	The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.	N525	These services are not covered when performed within the global period of another service.
CO-107	The related or qualifying claim/service was not identified on this claim.	MA66	Missing/incomplete/invalid principal procedure code.
CO-107	The related or qualifying claim/service was not identified on this claim.	N674	Not covered unless a pre-requisite procedure/service has been provided.
CO-108	Rent/purchase guidelines were not met.	N370	Billing exceeds the rental months covered/approved by the payer.
CO-109	Claim/service not covered by this payer/contractor. You must send the claim/service to the correct payer/contractor.	N418	Misrouted claim. See the payer's claim submission instructions.
CO-109	Claim/service not covered by this payer/contractor. You must send the claim/service to the correct payer/contractor.	N747	This is a misdirected claim/service. Submit the claim to the payer/plan where the patient resides.
CO-110	Billing date predates service date.	M52	Missing/incomplete/invalid "from" date(s) of service.
CO-119	Benefit maximum for this time period or occurrence has been reached.	M86	Service denied because payment already made for same/similar procedure within set time frame
CO-119	Benefit maximum for this time period or occurrence has been reached.	M90	Not covered more than once in a 12 month period.
CO-119	Benefit maximum for this time period or occurrence has been reached.	N362	The number of Days or Units of Service exceeds our acceptable maximum.
CO-119	Benefit maximum for this time period or occurrence has been reached.	N435	Exceeds number/frequency approved/allowed within time period without support documentation.
CO-119	Benefit maximum for this time period or occurrence has been reached.	N640	Exceeds number/frequency approved/allowed within time period.
CO-133	The disposition of this service line is pending further review.
CO-140	Patient/Insured health identification number and name do not match	MA36	Missing/incomplete/invalid patient name.
CO-140	Patient/Insured health identification number and name do not match	N382	Missing/incomplete/invalid patient identifier.
CO-146	Diagnosis was invalid for the date(s) of service reported.	M76	Missing/incomplete/invalid diagnosis or condition
CO-147	Provider contracted/negotiated rate expired or not on file.
CO-149	Lifetime benefit maximum has been reached for this service/benefit category.	N117	This service is paid only once in a patient's lifetime.
CO-164	Attachment/other documentation referenced on the claim was not received in a timely fashion.	N850	Missing/incomplete/invalid narrative explaining/describing this service/treatment.
CO-170	Payment is denied when performed/billed by this type of provider.	N95	This provider type/provider specialty may not bill this service.
CO-171	Payment is denied when performed/billed by this type of provider in this type of facility.	N428	Not covered when performed in this place of service.
CO-177	Patient has not met the required eligibility requirements.
CO-181	Procedure code was invalid on the date of service.	N56	Procedure code billed is not correct/valid for the services billed or the date of service billed.
CO-183	The referring provider is not eligible to refer the service billed. N	N574	Our records indicate the ordering/referring provider is of a type/specialty that cannot order or refer. Please verify that the claim ordering/referring provider.
CO-184	The prescribing/ordering provider is not eligible to prescribe/order the service billed.	N767	The Medicaid state requires provider to be enrolled in the member's Medicaid state program prior to any claim benefits being processed.
CO-190	Payment is included in the allowance for a Skilled Nursing Facility (SNF) qualified stay.	N538	A facility is responsible for payment to outside providers who furnish these services/supplies/drugs to its patients/residents.
CO-197	Precertification/authorization/notification/pre-treatment absent.
CO-198	Precertification/notification/authorization/pre-treatmentexceeded.	N351	Service date outside of the approved treatment plan service dates.
CO-198	Precertification/notification/authorization/pre-treatmentexceeded.	N362	The number of Days or Units of Service exceeds our acceptable maximum.
CO-198	Precertification/notification/authorization/pre-treatmentexceeded.	N435	Exceeds number/frequency approved/allowed within time period without support documentation.
199	Revenue code and Procedure code do not match.	N657	This should be billed with the appropriate code for these services.
204	This service/equipment/drug is not covered under the patient's current benefit plan.	N428	Not covered when performed in this place of service.
216	Based on the findings of a review organization.
216	Based on the findings of a review organization.
216	Based on the findings of a review organization.	N10	Adjustment based on the findings of a review organization/professional consult/manual adjudication/medical advisor/dental advisor/peer review.
234	This procedure is not paid separately.	M14	No separate payment for an injection administered during an office visit, and no payment for a full office visit if the patient ony received an injection.
234	This procedure is not paid separately.	N20	Service not payable with other service rendered on the same date.
234	This procedure is not paid separately.	N390	This service/report cannot be billed separately. 5
242	Services not provided by network/primary care providers.	N767	The Medicaid state requires provider to be enrolled in the member's Medicaid state program prior to any claim benefits being processed.
251	The attachment/other documentation that was received was the incorrect attachment/document. The expected attachment/document is still missing.	N28	Consent form requirements not fulfilled.
252	An attachment/other documentation is required to adjudicate this claim/service.	M23	Missing Invoice.
252	An attachment/other documentation is required to adjudicate this claim/service.	M127	Missing patient medical record for this service.
252	An attachment/other documentation is required to adjudicate this claim/service.	N26	Missing itemized bill/statement.
252	An attachment/other documentation is required to adjudicate this claim/service.	N28	Consent form requirements not fulfilled.
252	An attachment/other documentation is required to adjudicate this claim/service.	N706	Missing documentation.
258	Claim/service not covered when patient is in custody/incarcerated. Applicable federal, state or local authority may cover the claim/service.	N30	Patient ineligible for this service.
267	Claim/service spans multiple months.	N74	Resubmit with multiple claims, each claim covering services provided in only one calendar month.
272	Coverage/program guidelines were not met.	N20	Service not payable with other service rendered on the same date.
273	Coverage/program guidelines were exceeded.	N640	Exceeds number/frequency approved/allowed within time period
282	The procedure/revenue code is inconsistent with the type of bill.	MA30	Missing/incomplete/invalid type of bill.
284	Precertification/authorization/notification/pre-treatment number may be valid but does not apply to the billed services.	M62	Missing/incomplete/invalid treatment authorization code.
296	Precertification/authorization/notification/pre-treatment number may be valid but does not apply to the provider.	MA130	Your claim contains incomplete and/or invalid information, and no appeal rights are afforded because the claim is unprocessable. Please submit a new claim with the complete/correct information.
299	The billing provider is not eligible to receive payment for the service billed.	N767	The Medicaid state requires provider to be enrolled in the member's Medicaid state program prior to any claim benefits being processed.
299	The billing provider is not eligible to receive payment for the service billed.	N831	You have not responded to requests to revalidate your provider/supplier enrollment information.
A1	Claim/Service denied.	MA31	Missing/incomplete/invalid beginning and ending dates of the period billed.
A1	Claim/Service denied.	MA133	Claim overlaps inpatient stay. Rebill only those services rendered outside the inpatient stay.
A1	Claim/Service denied.	N47	Claim conflicts with another inpatient stay.
A1	Claim/Service denied.	N65	Procedure code or procedure rate count cannot be determined, or was not on file, for the date of service/provider
A8	Ungroupable DRG
A8	Ungroupable DRG
A8	Ungroupable DRG	N647	Adjusted based on diagnosis-related group (DRG).
B1	Non-covered visits	N113	Only one initial visit is covered per physician, group practice or provider.
B7	This provider was not certified/eligible to be paid for this procedure/service on this date of service.	N95	This provider type/provider specialty may not bill this service.
B7	This provider was not certified/eligible to be paid for this procedure/service on this date of service.	N570	Missing/incomplete/invalid credentialing data.
B9	Patient is enrolled in a Hospice.
B13	Previously paid. Payment for this claim/service may have been provided in a previous payment.	M86	Service denied because payment already made for same/similar procedure within set time frame.
B15	This service/procedure requires that a qualifying service/procedure be received and covered. The qualifying other service/procedure has not been received/adjudicated.	M51	Missing/incomplete/invalid procedure code(s).
B15	This service/procedure requires that a qualifying service/procedure be received and covered. The qualifying other service/procedure has not been received/adjudicated.	M122	Add-on code cannot be billed by itself.
B16	New Patient' qualifications were not met.	M86	Service denied because payment already made for same/similar procedure within set time frame.
B16	New Patient' qualifications were not met.	N113	Only one initial visit is covered per physician, group practice or provider.
B20	Procedure/service was partially or fully furnished by another provider.
B20	Procedure/service was partially or fully furnished by another provider.	M86	Service denied because payment already made for same/similar procedure within set time frame.
B20	Procedure/service was partially or fully furnished by another provider.	N538	A facility is responsible for payment to outside providers who furnish these services/supplies/drugs to its patients/residents.