Official X12 description
“This injury/illness is covered by the liability carrier.”
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 20 actually means
CARC 20 indicates the payer believes the service relates to an injury with active liability coverage (auto, homeowners, or third-party injury case). Rebill the liability carrier; the health plan typically only pays after the liability policy exhausts or denies. Subrogation may apply.
Common root causes
- Patient's injury is subject to a liability/third-party case.
- Accident indicator not checked at registration; health plan paid first by accident.
Prevention checklist
- Accident questionnaire at registration; capture liability insurer and claim number.
- Subrogation workflow to push to liability carrier first on all trauma claims.
Appeal strategy — step by step
Most CARC 20 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.
- 1Rebill the liability carrier.
- 2Once the liability carrier has paid/settled/denied, rebill the health plan with proof.
Sample appeal-letter language for CARC 20
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 20 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 20?
Out of 306 seeded CARCs, ranked by combined US monthly search volume for "CARC 20", "CO-20 denial", and "denial code 20".
Platform frequency ranks publish once the anonymized denial-rate pipeline reaches the publication threshold (strategy §12 Phase 2).
How QuickRCM prevents CARC 20
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 20
Under the CAQH CORE Payment and Remittance Uniform Use rule, health plans may pair CARC 20 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 |
| MA04 | Secondary payment cannot be considered without the identity of or payment information from the primary payer. The information was either not reported or was illegible. | CO, PI or PR | 3 |
| N723 | Patient must use Liability set-aside (LSA) funds to pay for the medical service or item. | CO, PI or PR | 3 |
| N725 | A liability insurer has reported having ongoing responsibility for medical services (ORM) for this diagnosis. | CO, PI or PR | 3 |
| N744 | Adjusted because the services may be related to an auto/other accident. | CO, PI or PR | 3 |
Frequently asked questions — CARC 20
What does CARC 20 mean?
CARC 20 is an X12 Claim Adjustment Reason Code. The official definition is: "This injury/illness is covered by the liability carrier." In plain English, the payer is telling you cARC 20 indicates the payer believes the service relates to an injury with active liability coverage (auto, homeowners, or third-party injury case). Rebill the liability carrier; the health plan typically only pays after the liability policy exhausts or denies. Subrogation may apply.
How do I resolve a CARC 20 (CO-20) denial?
Start with the most common root cause: Patient's injury is subject to a liability/third-party case. First step: Rebill the liability carrier. See the full remediation and appeal checklist on this page before filing a formal appeal.
Is CARC 20 patient responsibility?
No — CARC 20 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 20 look like on an EOB or 835 remittance?
On the 835 ERA, CARC 20 appears in Loop 2110 CAS segment as "CAS*CO*20*{amount}". On a paper EOB the same code prints in the Adjustment/Denial Reason column with the X12 description: "This injury/illness is covered by the liability carrier." — usually paired with one or more RARC remark codes in the same remittance line for additional context.
Can CARC 20 be appealed successfully?
Yes — when the root cause does not apply to the specific claim. Overturn rates are strongest when the appeal cites the X12 definition, the payer's own published policy, and documentation that rebuts the payer's rationale. The sample appeal language block above is a starting point; always adapt it to the payer's reconsideration form.
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.