Remark Codes — Complete List & Lookup

Browse all standardized Remark Codes (RARC) used on Medicare, Medicaid, and commercial payer remittance advice (835 ERA / EOB). Each code includes its RA835 mapping, adjustment group, reason code, and a dedicated resolution guide.

2,992

Total Remark Codes

Adjustment Groups

835

RA835 Mapped

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Looking for Denial Codes (CARC)?

Browse Claim Adjustment Reason Codes — the codes that explain why a payment was reduced or denied.

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Showing 1,201–1,250 of 2,818 remark codes in group CO

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Remark Code	Description	RA835 Code	Group	Reason Code
X586	PROTHROMBIN TIME (PT) HAS A MAXIMUM FREQUENCY OF SERVICE UNITS PER FREQUENCY VALUE QUALIFIER	N640 Exceeds number/frequency approved/allowed within time …	CO	151	View →
X587	SERUM IRON STUDIES ARE NOT COVERED BY MEDICARE WITHOUT AN APPROPRIATE DIAGNOSIS	N130 Consult plan benefit documents/guidelines for informat…	CO	204	View →
X588	SERUM IRON STUDIES ARE NOT COVERED BY MEDICARE WHEN BILLED MORE THAN ONCE IN A 90 DAY INTERVAL.	N640 Exceeds number/frequency approved/allowed within time …	CO	151	View →
X589	COLLAGEN CROSSLINKS ARE NOT COVERED BY MEDICARE WHEN BILLED WITHOUT AN APPROPRIATE SUPPORTING DIAGN…	N130 Consult plan benefit documents/guidelines for informat…	CO	204	View →
X59	SERVICE UNIT OUT OF RANGE FOR PROCEDURE (INACTIVE)	M53 Missing/incomplete/invalid days or units of service.	CO	151	View →
X590	GLYCATED HEMOGLOBIN/GLYCATED PROTEIN ARE NOT COVERED BY MEDICARE WHEN BILLED WITHOUT AN APPROPRIATE…	N130 Consult plan benefit documents/guidelines for informat…	CO	204	View →
X591	THYROID TESTING IS NOT COVERED BY MEDICARE WHEN BILLED WITHOUT AN APPROPRIATE SUPPORTING DIAGNOSIS	N130 Consult plan benefit documents/guidelines for informat…	CO	204	View →
X592	DIGOXIN THERAPEUTIC DRUG ASSAY IS NOT COVERED BY MEDICARE WHEN BILLED WITHOUT AN APPROPRIATE SUPPOR…	N130 Consult plan benefit documents/guidelines for informat…	CO	204	View →
X593	ALPHA-FETOPROTEIN IS NOT COVERED BY MEDICARE WHEN BILLED WITHOUT AN APPROPRIATE SUPPORTING DIAGNOSIS	N130 Consult plan benefit documents/guidelines for informat…	CO	204	View →
X594	CARCINOEMBRYONIC ANTIGEN IS NOT COVERED BY MEDICARE WHEN BILLED WITHOUT AN APPROPRIATE SUPPORTING D…	N130 Consult plan benefit documents/guidelines for informat…	CO	204	View →
X595	TUMOR ANTIGEN BY IMMUNOASSAY CA 125 IS NOT COVERED BY MEDICARE WHEN BILLED WITHOUT AN APPROPRIATE S…	N130 Consult plan benefit documents/guidelines for informat…	CO	204	View →
X596	TUMOR ANTIGEN BY IMMUNOASSAY CA 19-9 IS NOT COVERED BY MEDICARE WHEN BILLED WITHOUT AN APPROPRIATE …	N130 Consult plan benefit documents/guidelines for informat…	CO	204	View →
X597	PROSTATE SPECIFIC ANTIGEN IS NOT COVERED BY MEDICARE WHEN BILLED WITHOUT AN APPROPRIATE SUPPORTING …	N130 Consult plan benefit documents/guidelines for informat…	CO	204	View →
X598	PROSTATE SPECIFIC ANTIGEN IS NOT COVERED BY MEDICARE WHEN BILLED MORE THAN ONCE IN A 12 MONTH PERIOD	N640 Exceeds number/frequency approved/allowed within time …	CO	151	View →
X599	GAMMA GLUTAMYL TRANSFERASE IS NOT COVERED BY MEDICARE WHEN BILLED WITHOUT AN APPROPRIATE SUPPORTING…	N130 Consult plan benefit documents/guidelines for informat…	CO	204	View →
X6	ADMISSION DIAGNOSIS DESCRIBES AN EXTERNAL CAUSE OR REQUIRES THE ICD CODE FOR THE FIRST UNDERLYING D…	MA63 Missing/incomplete/invalid principal diagnosis.	CO	16	View →
X60	MULTIPLE BILATERAL PROCEDURES WITHOUT MODIFIER 50	N519 Invalid combination of HCPCS modifiers.	CO	16	View →
X600	HEPATITIS PANEL/ACUTE HEPATITIS PANEL IS NOT COVERED BY MEDICARE WHEN BILLED WITHOUT AN APPROPRIATE…	N130 Consult plan benefit documents/guidelines for informat…	CO	204	View →
X601	ALUMINUM LAB TEST IS NOT COVERED BY MEDICARE WHEN BILLED MORE THAN ONCE WITHIN A 3 MONTH PERIOD	N640 Exceeds number/frequency approved/allowed within time …	CO	151	View →
X602	HEARTSBREATH TEST IS NOT REASONABLE AND NECESSARY AND IS NOT COVERED BY CMS	N130 Consult plan benefit documents/guidelines for informat…	CO	204	View →
X603	BRACHYTHERAPY SOURCES PROCEDURE REQUIRES A VALID BRACHYTHERAPY PROCEDURE.	M84 Medical code sets used must be the codes in effect at …	CO	16	View →
X604	DIRECT ADMISSION OF PATIENT FOR HOSPITAL OBSERVATION CARE WHEN BILLED WITH CRITICAL CARE, EVALUATIO…	N55 Procedures for billing with group/referring/performing…	CO	16	View →
X605	DMEPOS ITEMS BILLED BY A DMEMAC PROVIDER WITH INVALID POS WILL BE DENIED.	M77 Missing/incomplete/invalid/inappropriate place of serv…	CO	5	View →
X606	MANUAL WHEELCHAIR OR WHEELCHAIR-SPECIAL SIZE MUST BE BILLED WITH MODIFIER KX	N572 This procedure is not payable unless appropriate non-p…	CO	16	View →
X607	GLYCATED HEMOGLOBIN/GLYCATED PROTEIN PROCEDURE IS NOT COVERED BY MEDICARE WHEN BILLED MORE THAN ONC…	N640 Exceeds number/frequency approved/allowed within time …	CO	151	View →
X608	CARCINOEMBRYONIC ANTIGEN IS NOT COVERED BY MEDICARE WHEN BILLED MORE THAN TWICE WITHIN A PATIENT'S …	N640 Exceeds number/frequency approved/allowed within time …	CO	151	View →
X609	A4606 (RE-USABLE PULSE OXIMETER) WITH MODIFIER U5 - 1 UNIT EVERY SIX CALENDAR MONTHS	N640 Exceeds number/frequency approved/allowed within time …	CO	151	View →
X61	INAPPROPRIATE SPECIFICATION OF BILATERAL PROCEDURE	M67 Missing/incomplete/invalid other procedure code(s).	CO	16	View →
X610	A4606 (RE-USABLE PULSE OXIMETER) WITH NO MODIFIER - 4 PER MONTH	N640 Exceeds number/frequency approved/allowed within time …	CO	151	View →
X611	A4623 (TRACHEOSTOMY, DISPOSABLE INNER CANNULA) WITH MODIFIER U3 - 31 PER CALENDAR MONTH	N640 Exceeds number/frequency approved/allowed within time …	CO	151	View →
X612	A4623 (TRACHEOSTOMY, DISPOSABLE INNER CANNULA) WITH NO MODIFIER - 1 PER CALENDAR MONTH	N640 Exceeds number/frequency approved/allowed within time …	CO	151	View →
X613	A7520 â 1 UNIT PER CALENDAR MONTH	N640 Exceeds number/frequency approved/allowed within time …	CO	151	View →
X614	A7520 WITH MODIFIER U1 - 1 PER CALENDAR MONTH	N640 Exceeds number/frequency approved/allowed within time …	CO	151	View →
X615	A7520 WITH MODIFIER U2 - 1 PER CALENDAR MONTH	N640 Exceeds number/frequency approved/allowed within time …	CO	151	View →
X616	A7521 - 1 PER CALENDAR MONTH	N640 Exceeds number/frequency approved/allowed within time …	CO	151	View →
X617	A7521 WITH MODIFIER U1 - 1 PER CALENDAR MONTH	N640 Exceeds number/frequency approved/allowed within time …	CO	151	View →
X618	A7521 WITH MODIFIER U2 - 1 PER CALENDAR MONTH	N640 Exceeds number/frequency approved/allowed within time …	CO	151	View →
X619	E0445 (OXIMETER DEVICE) WITH MODIFIER U4 - 1 PER FIVE ROLLING YEARS	N460 Incomplete/invalid Discharge Summary.	CO	151	View →
X62	INPATIENT PROCEDURE	M77 Missing/incomplete/invalid/inappropriate place of serv…	CO	5	View →
X620	E0445 WITH NO MODIFIER - 1 EVERY 6 MONTHS	N640 Exceeds number/frequency approved/allowed within time …	CO	151	View →
X621	IT IS INAPPROPRIATE TO PROVIDE HEPATITIS A/B VACCINES, INFLUENZA VACCINES OR PNEUMOCOCCAL PNEUMONIA…	N428 Not covered when performed in this place of service.	CO	5	View →
X622	A COMBINATION OF MODIFIERS GN, GO, OR GP CANNOT BE REPORTED ON THE SAME SERVICE LINE ON INSTITUTION…	N519 Invalid combination of HCPCS modifiers.	CO	16	View →
X623	THERAPY SERVICES MUST BE BILLED WITH A MODIFIER APPROPRIATE TO THE REVENUE CODE.	N572 This procedure is not payable unless appropriate non-p…	CO	16	View →
X624	ACCORDING TO CMS POLICY, PROCEDURES THAT ARE REDUCED SERVICES (MODIFIER 52) OR DISCONTINUED PRIOR T…	M53 Missing/incomplete/invalid days or units of service.	CO	222	View →
X625	MODIFIER Q0 OR MODIFIER Q1 CAN ONLY BE BILLED WHEN CONDITION CODE 30 AND BILL TYPE 0130-013Z (HOSPI…	N519 Invalid combination of HCPCS modifiers.	CO	16	View →
X626	BRACHYTHERAPY SOURCE BILLED WITHOUT AN APPROVED ASC SURGICAL PROCEDURE.	M84 Medical code sets used must be the codes in effect at …	CO	16	View →
X627	CONDITION CODE 44 (INPATIENT ADMISSION CHANGED TO OUTPATIENT) CAN ONLY BE BILLED WITH BILL TYPES 01…	MA30 Missing/incomplete/invalid type of bill.	CO	5	View →
X628	PER THE MEDICARE PHYSICIAN FEE SCHEDULE, PROCEDURE CODE DESCRIBES A PHYSICAL THERAPY SERVICES SUBMI…	M77 Missing/incomplete/invalid/inappropriate place of serv…	CO	5	View →
X629	MODIFIER ON PROC CODE INDICATES A REDUCTION.	N546 Payment represents a previous reduction based on the E…	CO	45	View →
X63	MUTUALLY EXCLUSIVE PROCEDURE THAT IS NOT ALLOWED BY NCCI EVEN IF APPROPRIATE MODIFIER IS PRESENT	M86 Service denied because payment already made for same/s…	CO	97	View →

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What is a Remark Code?

Remark Codes (RARC) are used on the 835 ERA and paper EOB to provide supplemental information about a claim adjustment. They always accompany a CARC (denial code) and clarify the reason for payment differences.

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Remark Code vs. Denial Code

A Denial Code (CARC) explains why payment was adjusted. A Remark Code (RARC) provides additional context or instructions. Both appear together on remittance — look for the CARC first, then the RARC for detail.

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How to Use This List

Search by code number or keyword, or filter by adjustment group (CO, PR, OA…). Click any code to see its full RA835 mapping, common causes, step-by-step resolution guide, and appeal tips.