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.
Browse Claim Adjustment Reason Codes — the codes that explain why a payment was reduced or denied.
| Remark Code | Description | RA835 Code | Group | Reason Code | |
|---|---|---|---|---|---|
| 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 → |
| X630 | PER CMS POLICY, PROCEDURE CODE DESCRIBES HYPERTHERMIA SERVICES WHICH ARE ONLY COVERED WHEN BILLED I… |
M84
Medical code sets used must be the codes in effect at … |
CO | 16 | View → |
| X631 | (HOSPITAL DISCHARGE SERVICES) WAS BILLED ON PRIOR DAY ON CLAIM. |
N522
Duplicate of a claim processed, or to be processed, as… |
CO | 18 | View → |
| X632 | CO-SURGEONS COULD BE PAID, THOUGH SUPPORTING DOCUMENTATION IS REQUIRED TO ESTABLISH THE MEDICAL NEC… |
N706
Missing documentation. |
CO | 163 | View → |
| X633 | PER THE MEDICARE PHYSICIAN FEE SCHEDULE, PROCEDURE CODE DESCRIBES A PHYSICIAN INTERPRETATION FOR SE… |
M77
Missing/incomplete/invalid/inappropriate place of serv… |
CO | 5 | View → |
| X634 | PER CMS GUIDELINES, CO-SURGEON CLAIMS WHEN BOTH SURGEONS HAVE THE SAME SUBSPECIALTY FOR PROCEDURES … |
N130
Consult plan benefit documents/guidelines for informat… |
CO | 204 | View → |
| X635 | PER AMA GUIDELINES, INITIAL HOSPITAL OR BIRTHING CENTER CARE WILL BE DENIED WHEN THE NEWBORN HAS RE… |
M84
Medical code sets used must be the codes in effect at … |
CO | 16 | View → |
| X64 | CODE2 OF A CODE PAIR 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 → |
| X644 | PROCEDURE LINE IS A POSSIBLE DUPLICATE OF CLAIM. PROCEDURE CAN NOT BE BILLED ON SAME DOS WITH DIFFE… |
N522
Duplicate of a claim processed, or to be processed, as… |
CO | 18 | View → |
| X645 | INJECTIONS, LABS REPORTS, AND TESTS MUST BE BILLED WITH SPECIFIC PROCEDURE CODE ON ONE SERVICE SECT… |
N381
Alert: Consult our contractual agreement for restricti… |
CO | 16 | View → |
| X646 | THERAPY MUST BE BILLED WITH ONE SERVICE SECTION FOR EACH ITEM (PT, OT OR ST) OR SERVICE PROVIDED TO… |
N381
Alert: Consult our contractual agreement for restricti… |
CO | 272 | View → |
| X647 | MODIFIER 25/59 CAN NOT BE BILLED MULTIPLE TIMES FOR THE SAME SERVICE RENDERED ON THE SAME DOS. |
N130
Consult plan benefit documents/guidelines for informat… |
CO | 272 | View → |
| X648 | PRICING MODIFIERS SHOULD NOT BE SUBMITTED MULTIPLE TIMES ON THE SAME PROCEDURE. |
N130
Consult plan benefit documents/guidelines for informat… |
CO | 272 | View → |
| X649 | IMPROPER BILLING OF BILATERAL PROCEDURE. UNITS MUST BE 1. |
M53
Missing/incomplete/invalid days or units of service. |
CO | 222 | View → |
| X65 | MEDICAL VISIT ON THE SAME DAY AS A TYPE T OR S PROCEDURE WITHOUT MODIFIER 25 |
N519
Invalid combination of HCPCS modifiers. |
CO | 16 | View → |
| X650 | AUDIOLOGY INPATIENT CHARGES ARE INCLUDED IN THE REIMBURSEMENT TO A HOSPITAL AND ARE NOT TO BE BILLE… |
N130
Consult plan benefit documents/guidelines for informat… |
CO | 272 | View → |
| X651 | PROVIDER TAXONOMY CANNOT BILL IN PLACE OF SERVICE . |
N288
Missing/incomplete/invalid rendering provider taxonomy. |
CO | 8 | View → |
| X652 | DME SUPPLIERS CANNOT BILL IN PLACE OF SERVICE WHEN THE PATIENT IS 21 YEARS OR OLDER. |
M77
Missing/incomplete/invalid/inappropriate place of serv… |
CO | 5 | View → |
| X653 | REVENUE CODE INVALID FOR CATEGORY OF SERVICE. |
M50
Missing/incomplete/invalid revenue code(s). |
CO | 16 | View → |
| X654 | OCCURRENCE CODE 50 IS NO LONGER VALID TO BYPASS PA FOR POST-DISCHARGE SERVICES. OCCURRENCE CODE 42 … |
M45
Missing/incomplete/invalid occurrence code(s). |
CO | 16 | View → |
| X655 | PROCEDCURE CODE CAN ONLY BE USED BY OUTPATIENT FACILITIES BILLED ON AN INSTUTIONAL CLAIM (C CODES) |
M51
Missing/incomplete/invalid procedure code(s). |
CO | 16 | View → |
| X656 | WHEN MULTIPLE GENERAL ANESTHESIA SERVICE CODES, ONLY THE HIGHEST SUBMITTED CHARGE AMOUNT WILL BE PA… |
N634
The allowance is calculated based on anesthesia time u… |
CO | 59 | View → |
| X657 | INCORRECT BILLING OF ASSISTANT SURGEON MODIFIERS FOR CRITICAL ACCESS PROFESSIONAL FEES REVENUE CODE… |
N130
Consult plan benefit documents/guidelines for informat… |
CO | 272 | View → |
| X658 | INCORRECT BILLING OF CO-SURGEON MODIFIER FOR CRITICAL ACCESS PROFESSIONAL FEES REVENUE CODE.; REVEN… |
N130
Consult plan benefit documents/guidelines for informat… |
CO | 272 | View → |
| X659 | C CODES CANNOT BE BILLED WITH REVENUE CODES REPRESENTING PROFESSIONAL FEES; REVENUE CODES 0960-0989. |
N130
Consult plan benefit documents/guidelines for informat… |
CO | 272 | View → |
| X66 | INVALID MODIFIER |
N519
Invalid combination of HCPCS modifiers. |
CO | 182 | View → |
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.
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.
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.