CO-56: Procedure / Treatment Not Deemed Effective

What Does CO-56 Mean?

CO 56 is a contractual obligation adjustment where the payer has determined the treatment is not effective. The provider cannot bill the patient and must demonstrate effectiveness through clinical evidence to overturn the denial. This is particularly common in therapy settings where utilization review has determined the patient has plateaued. The appeal must include objective functional assessments and measurable improvement data — subjective provider notes alone are typically insufficient.

CARC 56 is the payer's clinical judgment that the treatment or procedure billed has not demonstrated effectiveness for the patient's specific condition. This differs from CARC 50 (not medically necessary) and CARC 55 (experimental) in an important way: the payer is not saying the treatment lacks evidence or is not needed — they are saying the evidence shows it does not work, or that it has not produced measurable results for this patient.

This denial frequently appears in rehabilitation settings (physical therapy, occupational therapy, speech therapy) where a payer determines that the patient has reached a treatment plateau and continued sessions are no longer producing functional improvement. It also applies to treatments where the payer has reviewed the clinical literature and concluded the procedure is not effective for the specific diagnosis billed. A common scenario is a therapy clinic that has been seeing a patient for several months, and the payer's utilization review determines that objective functional scores are no longer improving.

The group code matters significantly. CO 56 means the provider must absorb the cost or appeal — the key is presenting clinical evidence of effectiveness, including objective functional assessments and measurable improvement data. PR 56 means the patient is responsible, typically because their plan excludes treatments the payer deems ineffective. For either group code, the appeal strategy centers on demonstrating that the treatment has produced or will produce measurable clinical benefit.

Common Causes

How to Resolve

Demonstrate treatment effectiveness through clinical documentation showing measurable patient improvement and peer-reviewed evidence supporting the treatment for the specific condition.

1. Document measurable improvement Compile standardized outcome measures and functional assessments that demonstrate the patient has improved or is expected to improve with continued treatment. Include baseline and current scores.
2. Address the payer's criteria Review the payer's specific effectiveness criteria and structure the appeal to address each criterion with supporting evidence.
3. File appeal with evidence package Submit the appeal with objective improvement data, clinical practice guidelines, and a physician narrative explaining the treatment plan and expected outcomes.

Common RARC Pairings

The RARC code tells you exactly what triggered the CO-56:

How to Prevent CO-56

• Document objective functional improvement at every treatment session using standardized assessment tools.
• Obtain prior authorization for treatments where effectiveness may be questioned by the payer.
• Review payer medical policies on treatment effectiveness criteria before initiating care plans.
• Use appropriate diagnosis codes that accurately reflect the condition being treated.

General Prevention

• Obtain prior authorization before rendering treatments where effectiveness may be questioned by the payer.
• Document measurable patient progress at each visit using objective functional assessments.
• Review the payer's medical policies on treatment effectiveness criteria before initiating care plans.
• Ensure progress notes demonstrate ongoing medical necessity and clinical improvement throughout the treatment course.
• Use appropriate CPT and ICD-10 codes that accurately reflect the treatment and condition to avoid triggering effectiveness edits.

Also Filed As

The same CARC 56 may appear with different Group Codes:

Related Denial Codes