The insurer decided the service was not medically necessary based on their coverage criteria. This is one of the most common and most frequently overturned denials.
Appeal with your doctor clinical notes, test results, and a letter from your physician explaining why the service was necessary. Reference the insurer specific medical necessity criteria in your appeal. CO-50 denials are among the most commonly overturned in external review.
Appeal outlook: High -- approximately 44% of internal appeals succeed industry-wide
Recommended tool
Bill Advantage can analyze your denial and generate a ready-to-send appeal or dispute letter in minutes.
Open Prior Authorization Appeal GeneratorA prior authorization denial is not final. Learn the exact steps to appeal a prior auth denial in 2026, including what documentation wins and when to escalate.
Read articleSupplemental Claim, Higher-Level Review, or Board Appeal: Which One Should You File?The VA offers three appeal pathways after a denial. Choosing the wrong one can cost you months and money. Here is how to decide which fits your situation.
Read articleWhat Does Insurance Denial Code CO-50 Mean and How Do You Appeal ItCO-50 means your insurer says the service is not medically necessary. Here is what that means, why it happens, and how to fight it.
Read articleWhat Is a Denial Code and What Does Mine MeanDenial codes on your EOB explain why a claim was denied. Learn what the most common codes mean in 2026 and the exact steps to fix or appeal each one.
Read articleWhat to Do When Insurance Denies a ClaimInsurance denied your claim? Learn the exact steps to appeal a health insurance denial in 2026, from reading the denial letter to external independent review.
Read article