Instantly find explanations, causes, and resolution steps for every Claim Adjustment Reason Code (CARC) and Remark Code.
Claim Adjustment Reason Codes (CARC) explain why a payment differs from what was billed. Every 835 ERA and EOB uses these standardized codes.
Search any code or keyword above. Each page includes the full description, common causes, resolution steps, and appeal guidance.
Each denial code page also links to a dedicated Remark Code page — optimized for providers searching for ERA remark code context.
Most denials are reversible. Our guides walk you through the correct steps to correct, resubmit, or formally appeal each denial type.
| Code | Description | View |
|---|---|---|
| MA12 | You have not established that you have the right under the law to bill for services f… | Details → |
| MA12 | You have not established that you have the right under the law to bill for services f… | Details → |
| MA120 | Missing/incomplete/invalid CLIA certification number. | Details → |
| MA120 | Missing/incomplete/invalid CLIA certification number. | Details → |
| MA121 | Missing/incomplete/invalid x-ray date. | Details → |
| MA121 | Missing/incomplete/invalid x-ray date. | Details → |
| MA122 | Missing/incomplete/invalid initial treatment date. | Details → |
| MA122 | Missing/incomplete/invalid initial treatment date. | Details → |
| MA123 | Your center was not selected to participate in this study, therefore, we cannot pay f… | Details → |
| MA123 | Your center was not selected to participate in this study, therefore, we cannot pay f… | Details → |
| MA124 | Processed for IME only. | Details → |
| MA124 | Processed for IME only. | Details → |
| MA125 | Per legislation governing this program, payment constitutes payment in full. | Details → |
| MA125 | Per legislation governing this program, payment constitutes payment in full. | Details → |
| MA126 | Pancreas transplant not covered unless kidney transplant performed. | Details → |
| MA126 | Pancreas transplant not covered unless kidney transplant performed. | Details → |
| MA127 | Reserved for future use. | Details → |
| MA127 | Reserved for future use. | Details → |
| MA128 | Missing/incomplete/invalid FDA approval number. | Details → |
| MA128 | Missing/incomplete/invalid FDA approval number. | Details → |
| MA129 | This provider was not certified for this procedure on this date of service. | Details → |
| MA129 | This provider was not certified for this procedure on this date of service. | Details → |
| MA13 | Alert: You may be subject to penalties if you bill the patient for amounts not report… | Details → |
| MA13 | Item(s) billed did not have a valid ordering physician name | Details → |
| MA13 | Alert: You may be subject to penalties if you bill the patient for amounts not report… | Details → |
| MA130 | Your claim contains incomplete and/or invalid information, and no appeal rights are a… | Details → |
| MA130 | Your claim contains incomplete and/or invalid information, and no appeal rights are a… | Details → |
| MA131 | Physician already paid for services in conjunction with this demonstration claim. You… | Details → |
| MA131 | Physician already paid for services in conjunction with this demonstration claim. You… | Details → |
| MA132 | Adjustment to the pre-demonstration rate. | Details → |
| MA132 | Adjustment to the pre-demonstration rate. | Details → |
| MA133 | Claim overlaps inpatient stay. Rebill only those services rendered outside the inpati… | Details → |
| MA133 | Claim overlaps inpatient stay. Rebill only those services rendered outside the inpati… | Details → |
| MA134 | Missing/incomplete/invalid provider number of the facility where the patient resides. | Details → |
| MA134 | Missing/incomplete/invalid provider number of the facility where the patient resides. | Details → |
| MA14 | Alert: The patient is a member of an employer-sponsored prepaid health plan. Services… | Details → |
| MA14 | Alert: The patient is a member of an employer-sponsored prepaid health plan. Services… | Details → |
| MA15 | Alert: Your claim has been separated to expedite handling. You will receive a separat… | Details → |
| MA15 | Alert: Your claim has been separated to expedite handling. You will receive a separat… | Details → |
| MA16 | The patient is covered by the Black Lung Program. Send this claim to the Department o… | Details → |
| MA16 | The patient is covered by the Black Lung Program. Send this claim to the Department o… | Details → |
| MA17 | We are the primary payer and have paid at the primary rate. You must contact the pati… | Details → |
| MA17 | We are the primary payer and have paid at the primary rate. You must contact the pati… | Details → |
| MA18 | Alert: The claim information is also being forwarded to the patient's supplemental in… | Details → |
| MA18 | Alert: The claim information is also being forwarded to the patient's supplemental in… | Details → |
| MA19 | Alert: Information was not sent to the Medigap insurer due to incorrect/invalid infor… | Details → |
| MA19 | Alert: Information was not sent to the Medigap insurer due to incorrect/invalid infor… | Details → |
| MA20 | Skilled Nursing Facility (SNF) stay not covered when care is primarily related to the… | Details → |
| MA20 | Skilled Nursing Facility (SNF) stay not covered when care is primarily related to the… | Details → |
| MA21 | SSA records indicate mismatch with name and sex. | Details → |
| MA21 | SSA records indicate mismatch with name and sex. | Details → |
| MA22 | Payment of less than $1.00 suppressed. | Details → |
| MA22 | Payment of less than $1.00 suppressed. | Details → |
| MA23 | Demand bill approved as result of medical review. | Details → |
| MA23 | Demand bill approved as result of medical review. | Details → |
| MA24 | Christian Science Sanitarium/ Skilled Nursing Facility (SNF) bill in the same benefit… | Details → |
| MA24 | Christian Science Sanitarium/ Skilled Nursing Facility (SNF) bill in the same benefit… | Details → |
| MA25 | A patient may not elect to change a hospice provider more than once in a benefit peri… | Details → |
| MA25 | A patient may not elect to change a hospice provider more than once in a benefit peri… | Details → |
| MA26 | Alert: Our records indicate that you were previously informed of this rule. | Details → |
Medical claim denial codes — formally known as Claim Adjustment Reason Codes (CARC) — are standardized identifiers maintained by the X12 standards body and used across all Medicare, Medicaid, and commercial payer 835 electronic remittance transactions. When a claim is paid at a different amount than billed, at least one CARC code must accompany the remittance advice to indicate the specific reason for the adjustment.
The most frequently encountered codes include CO-16 (missing or invalid claim information), CO-45 (charges exceeding fee schedule), PR-1 (patient deductible), CO-29 (timely filing deadline exceeded), and CO-4 (procedure code inconsistent with modifier). Each represents a distinct, actionable reason that has a defined resolution pathway.