CO-19: work-related injury, workers’ compensation liability.

What X12 says CARC 19 means

This is a work-related injury/illness and thus the liability of the Worker's Compensation Carrier.

CARC 19 · Start 01/01/1995, last modified 09/30/2007.

In plain terms: The injury or illness is work-related, so the workers' compensation carrier is liable.

What it means on a remittance

The payer is saying that a work injury or illness belongs with the workers’ compensation carrier, not with the health plan. CARC 20 is the sibling code for a liability carrier, and CARC 21 covers a no-fault carrier.

Typical causes

• The claim form or the patient’s history indicates a work-related injury.
• The patient told the provider the injury happened at work, or an employer report exists.
• The claim’s accident or employment indicators were filled in as work-related by mistake.
• A workers’ compensation claim exists for the same body part or date of injury.

These are common billing patterns, not a diagnosis of your claim. The remittance and the payer's policy decide.

What to check

1. Ask the patient whether the injury or illness is work-related and whether a workers’ compensation claim was filed.
2. Get the carrier name, claim number and date of injury.
3. Check the employment-related indicator on your claim.
4. Check the filing rules of your state’s workers’ compensation system.

Correct, resubmit or appeal

If it is work-related, bill the workers’ compensation carrier with its claim number. If it is not, correct the indicators and send the payer a statement or record that supports your position, then ask for reprocessing.

Medicare dates that apply

A Medicare redetermination request must be filed within 120 calendar days from the date a party receives the notice of the initial determination; receipt is presumed 5 calendar days after the notice date unless there is evidence to the contrary (42 CFR 405.942(a)), and a late request can be considered for good cause (405.942(b)). Other payers set their own appeal windows in the contract or plan documents, so read the notice for the date. The tool above runs the date math.

Related codes

X12 does not publish a table that pairs each code with remark codes; the payer picks the remark code and prints it beside the CARC on the same remittance line.

Other codes: CARC 20 (liability carrier), CARC 22 (may be covered by another payer) and the full lookup.

Worked example (hypothetical)

A shoulder injury visit denies with CO-19. The patient says he was hurt on a job site. The biller gets the employer’s carrier and claim number and bills that carrier.

Sources

• X12: Claim Adjustment Reason Codes — code text, usage notes and dates (list dated 10/30/2026, retrieved 2026-11-02)
• 42 CFR 405.942 — eCFR, current through 2026-10-29 (retrieved 2026-11-02)

Code descriptions are X12 copyrighted material, quoted here only for the codes on this page and linked to the owner. For the full lists, use X12. The X12 text and the Medicare rule above were read from these pages on November 2, 2026. Causes, checks and examples are general billing practice written for this page, not X12 content. Payers revise code lists, contracts and policies, so confirm anything that affects a claim or a deadline with the payer.