Official X12 description
“Treatment was deemed by the payer to have been rendered in an inappropriate or invalid place of service.”
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 58 actually means
CARC 58 denies because the POS code on the claim does not match what the payer considers appropriate for the service — often an outpatient surgery billed with an office POS, or a hospital-based procedure billed with a clinic POS. Correct the POS (and, for hospital-based clinics, the site-of-service differential rules) and rebill.
Common root causes
- Wrong POS on the 837 (POS 11 vs 22 vs 24).
- Hospital-based-outpatient departments using POS 11 when POS 22 is required.
Prevention checklist
- POS mapping by rendering location, scrubber-enforced.
- Provider-enrollment file includes POS rules per site.
Appeal strategy — step by step
Most CARC 58 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.
- 1Correct the POS and submit a corrected claim; no narrative appeal needed.
Sample appeal-letter language for CARC 58
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 58 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 58?
Out of 306 seeded CARCs, ranked by combined US monthly search volume for "CARC 58", "CO-58 denial", and "denial code 58".
Platform frequency ranks publish once the anonymized denial-rate pipeline reaches the publication threshold (strategy §12 Phase 2).
How QuickRCM prevents CARC 58
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 58
Under the CAQH CORE Payment and Remittance Uniform Use rule, health plans may pair CARC 58 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 |
| M2 | Not paid separately when the patient is an inpatient. | CO, PI or PR | 3 |
| M77 | Missing/incomplete/invalid/inappropriate place of service. | CO, PI or PR | 3 |
| N87 | Home use of biofeedback therapy is not covered. | 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 |
| N386 | This decision was based on a National Coverage Determination (NCD). An NCD provides a coverage determination as to whether a particular item or service is covered. A copy of this policy is available at www.cms.gov/mcd/search.asp. If you do not have web access, you may contact the contractor to request a copy of the NCD. | CO, PI or PR | 3 |
| N428 | Not covered when performed in this place of service. | CO, PI or PR | 3 |
| N732 | Services performed at an unlicensed facility are not reimbursable. | CO, PI or PR | 3 |
| N760 | This facility is not authorized to receive payment for the service(s). | CO, PI or PR | 3 |
The rule behind CARC 58
CARC 58 means the payer judged the place of service inappropriate or invalid for the service. Compare the POS on the line with the setting definitions and the Medicare facility or non-facility designation for each code, and with where the patient was registered on the date of service; a corrected claim with the right code usually resolves it.
Frequently asked questions — CARC 58
What does CARC 58 mean?
CARC 58 is an X12 Claim Adjustment Reason Code. The official definition is: "Treatment was deemed by the payer to have been rendered in an inappropriate or invalid place of service." In plain English, the payer is telling you cARC 58 denies because the POS code on the claim does not match what the payer considers appropriate for the service — often an outpatient surgery billed with an office POS, or a hospital-based procedure billed with a clinic POS. Correct the POS (and, for hospital-based clinics, the site-of-service differential rules) and rebill.
How do I resolve a CARC 58 (CO-58) denial?
Start with the most common root cause: Wrong POS on the 837 (POS 11 vs 22 vs 24). First step: Correct the POS and submit a corrected claim; no narrative appeal needed. See the full remediation and appeal checklist on this page before filing a formal appeal.
Is CARC 58 patient responsibility?
No — CARC 58 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 58 look like on an EOB or 835 remittance?
On the 835 ERA, CARC 58 appears in Loop 2110 CAS segment as "CAS*CO*58*{amount}". On a paper EOB the same code prints in the Adjustment/Denial Reason column with the X12 description: "Treatment was deemed by the payer to have been rendered in an inappropriate or invalid place of service." — usually paired with one or more RARC remark codes in the same remittance line for additional context.
Which RARC is paired with CARC 58?
CARC 58 is commonly observed with RARC M77. 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.