CO-19 denial code
This is a work-related injury and is the liability of the workers compensation carrier
How to fix it
Confirm with the patient and employer whether a workers compensation claim exists, obtain the carrier and claim number, and bill that carrier.
How to prevent it
Ask about work-relatedness at registration for any injury presentation. Discovering it after billing wastes a filing window.
In practice
A patient is seen for a shoulder injury and gives their commercial insurance at the front desk. The claim returns CO-19: this is a work-related injury and is the liability of the workers compensation carrier.
The injury happened at work. The patient did not mention it, and nobody asked, so a claim was submitted to a payer that was never responsible for it.
The recovery is to obtain the employer, the workers compensation carrier and the claim number, then bill that carrier. The difficulty is time: weeks have passed, workers compensation filing rules differ from commercial ones, and the delay is now working against a deadline nobody was watching.
What sits behind it
The single question that prevents most CO-19 is asked at registration and takes five seconds: did this happen at work. It is skipped because injury presentations are triaged clinically rather than administratively, and the front desk collects insurance rather than causation.
Workers compensation is not health insurance and does not behave like it. It is a separate system with its own fee schedules set by state, its own authorisation rules, its own forms, and filing deadlines that are frequently shorter than commercial ones. A claim redirected there late is entering a process with less tolerance for delay, not more.
There is also a patient protection worth knowing. Where an injury is compensable, the patient generally cannot be balance billed for the difference — the workers compensation fee schedule is the payment, and pursuing the patient for a shortfall is prohibited in most jurisdictions.
Related codes
Terms used here — Coordination of Benefits · Eligibility Verification · Timely Filing
How we handle it — Eligibility Verification · Denial Management · AR Management
Primary sources
The rules behind CO-19, at the bodies that publish them.
- Workers' compensation medical billing (opens in a new tab)
US Department of Labor, OWCP — Federal workers' compensation fee schedule and billing requirements. State programs differ, but the structural rules are the same: a separate payer with its own schedule.
- Medicare Secondary Payer Manual (opens in a new tab)
Centers for Medicare & Medicaid Services — When Medicare pays second, and to whom the claim goes first. Coordination-of-benefits denials are resolved here rather than with the patient.
- Medicare Claims Processing Manual (opens in a new tab)
Centers for Medicare & Medicaid Services — The operative manual for how Medicare claims must be coded, submitted, adjusted and appealed. When a payer policy and a vendor's advice disagree, this settles it.
Every denial code with a guide
Authorization
Bundling
Contractual
Coverage
Data quality
Documentation
Eligibility
Liability and workers comp
- CO-19Workers Compensation Liability
Patient responsibility
Provider eligibility
Timely filing
Looking for a different code? Search all 190 CARC and RARC codes
Questions about CO-19
Confirm with the patient and their employer whether a workers compensation claim was filed, obtain the carrier and claim number, and bill that carrier. Move quickly — workers compensation filing deadlines are often shorter than commercial ones and weeks have usually already passed.
Generally not where the injury is compensable. The workers compensation fee schedule constitutes payment, and balance billing the patient for the difference is prohibited in most jurisdictions.
Until the dispute is resolved the claim sits between two payers. Some states require the health plan to pay pending determination, with a right of recovery afterwards. Document the dispute and keep both claims alive rather than letting either deadline pass.
Ask whether the injury happened at work, at registration, for every injury presentation. It takes seconds and it is the only reliable prevention, because nothing in an eligibility check reveals causation.
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