Official X12 description
“Previously paid. Payment for this claim/service may have been provided in a previous payment.”
Source: X12 Claim Adjustment Reason Codes. The X12 External Code Lists are the single authoritative source for every CARC descriptor — always verify against the current release before building a claim-scrub rule.
What CARC B13 actually means
CARC B13 tells you the payer considers this line a duplicate of a previously processed claim that already paid (same patient, provider, date, procedure). Before reworking, pull the prior 835 and confirm whether the first payment was truly for the same service or a different encounter. If distinct, rebill with the appropriate distinct-service modifier and a corrected note; if the first payment was correct, post the duplicate denial and close.
Common root causes
- A prior claim/line was already paid for the same DOS, member, and procedure — often from a resubmission loop.
- Global-surgery overlap: a service inside a global window is seen as already-paid bundled care.
- Two encounters on the same date that the payer reads as one (missing XE/XS/XU or anatomical modifier).
Prevention checklist
- Claim-status check (276/277) before any resubmission to avoid unintended duplicates.
- Surgical charge posting rules that flag post-op visits inside the global window; use modifier 24/79 where clinically appropriate.
Appeal strategy — step by step
Most CARC B13 denials clear faster with the right remediation than with a formal appeal. Work the steps in order and escalate only when a lower-effort path has been ruled out.
- 1Pull the 835 for the original paid claim and confirm the prior service matches: provider, DOS, CPT, modifier, place of service.
- 2If services were genuinely distinct, submit a corrected claim with the appropriate distinct-procedure or separate-encounter modifier and a brief narrative.
Sample appeal-letter language for CARC B13
Edit the bracketed fields before sending. This template is a starting point; a payer-specific appeal form may still be required — check the provider portal first.
Payer-specific notes
Payer-specific behavior for CARC B13 publishes here as the QuickIntell anonymized denial ETL ingests sufficient volume. In the meantime, consult the payer directory for the relevant provider manual and appeal form.
How common is CARC B13?
Out of 306 seeded CARCs, ranked by combined US monthly search volume for "CARC B13", "CO-B13 denial", and "denial code B13".
Platform frequency ranks publish once the anonymized denial-rate pipeline reaches the publication threshold (strategy §12 Phase 2).
How QuickRCM prevents CARC B13
QuickRCM catches the root causes above before the 837 leaves the clearinghouse:
- Claim-scrub rules fire on every root cause listed above — the scrub references the same X12 CAS segment logic that drives the denial, so what the payer checks, QuickRCM checks first.
- When a denial lands, QuickRCM routes it to the correct worker with the documentation bundle already attached (op note, LCD citation, modifier rationale, EOB, primary 835).
- Appeal templates tuned to each CARC (including this one) pull the supporting facts from the claim and fill the bracketed fields automatically.
CAQH CORE code combinations for CARC B13
Under the CAQH CORE Payment and Remittance Uniform Use rule, health plans may pair CARC B13 only with the remark codes and group codes below for the defined business scenario 3 (Billed service not covered by the health plan). A combination outside this list on an 835 is itself a payer compliance issue worth raising.
| RARC | Remark description | Group code | Scenario |
|---|---|---|---|
| (no RARC) | CARC used without a remark code | CO, PI or PR | 3 |
| M86 | Service denied because payment already made for same/similar procedure within set time frame. | CO, PI or PR | 3 |
| M97 | Not paid to practitioner when provided to patient in this place of service. Payment included in the reimbursement issued the facility. | CO, PI or PR | 3 |
| N10 | Adjustment based on the findings of a review organization/professional consult/manual adjudication/medical advisor/dental advisor/peer review. | CO, PI or PR | 3 |
| N115 | This decision was based on a Local Coverage Determination (LCD). An LCD provides a guide to assist in determining whether a particular item or service is covered. A copy of this policy is available at www.cms.gov/mcd, or if you do not have web access, you may contact the contractor to request a copy of the LCD. | CO, PI or PR | 3 |
| N347 | Your claim for a referred or purchased service cannot be paid because payment has already been made for this same service to another provider by a payment contractor representing the payer. | CO, PI or PR | 3 |
| N472 | Payment for this service has been issued to another provider. | CO, PI or PR | 3 |
Frequently asked questions — CARC B13
What does CARC B13 mean?
CARC B13 is an X12 Claim Adjustment Reason Code. The official definition is: "Previously paid. Payment for this claim/service may have been provided in a previous payment." In plain English, the payer is telling you cARC B13 tells you the payer considers this line a duplicate of a previously processed claim that already paid (same patient, provider, date, procedure). Before reworking, pull the prior 835 and confirm whether the first payment was truly for the same service or a different encounter. If distinct, rebill with the appropriate distinct-service modifier and a corrected note; if the first payment was correct, post the duplicate denial and close.
How do I resolve a CARC B13 (CO-B13) denial?
Start with the most common root cause: A prior claim/line was already paid for the same DOS, member, and procedure — often from a resubmission loop. First step: Pull the 835 for the original paid claim and confirm the prior service matches: provider, DOS, CPT, modifier, place of service. See the full remediation and appeal checklist on this page before filing a formal appeal.
Is CARC B13 patient responsibility?
No — CARC B13 is typically carried under CO (Contractual Obligation) or OA (Other Adjustment), which means it is the provider's responsibility, not the patient's. Do not bill the patient unless the 835 CAS group code is PR.
What does CARC B13 look like on an EOB or 835 remittance?
On the 835 ERA, CARC B13 appears in Loop 2110 CAS segment as "CAS*CO*B13*{amount}". On a paper EOB the same code prints in the Adjustment/Denial Reason column with the X12 description: "Previously paid. Payment for this claim/service may have been provided in a previous payment." — usually paired with one or more RARC remark codes in the same remittance line for additional context.
Which RARC is paired with CARC B13?
CARC B13 is commonly observed with RARC M80, N522. The RARC narrows the reason — for example, pointing at a missing modifier, an LCD citation, or a specific policy. Fix the underlying CARC first; the RARC usually clears with the corrected claim.
Disclaimer
This page is operational reference for medical-billing professionals. It is not legal, clinical, or contractual advice. X12 code descriptors are maintained by the X12 External Code Lists; always verify against the current X12 release and the payer's own published policy before submitting or appealing a claim.