Top 10 Prior Authorization Denial Reasons in 2026 (How to Beat Each)
Only 10% of PA denials get appealed but 50%+ of appeals succeed. The 10 most common denial reasons and the clinical language that flips each.
Why This Matters
Roughly 20% of all prior authorizations are denied on first submission, and only about 10% of those denials are ever appealed — even though appeal success rates exceed 50%. Understanding the most common denial reasons is the fastest way to reduce administrative burden and get patients on therapy.
1. Step Therapy Not Completed
The single most common denial. Payers require documentation that less expensive alternatives were tried first. Beat it by listing every prior therapy with dates, doses, and discontinuation reasons. If contraindicated, cite the contraindication.
2. Medical Necessity Not Established
Vague clinical reasoning. The fix: cite the specific FDA indication, link to a guideline recommendation, and document the patient's clinical features that match the indication.
3. Non-Formulary
Drug is not on the plan's preferred list. Submit a formulary exception request with clinical justification for why the formulary alternative is inappropriate.
4. Quantity Limit Exceeded
The prescribed dose exceeds the plan's default. Cite FDA labeling for higher doses if applicable, or document weight-based dosing.
5. Off-Label Use
The indication isn't in the FDA label. Cite peer-reviewed evidence (RCTs, NCCN compendia, AHFS DI) supporting the off-label use.
6. Site of Care Restriction
Payer wants the infusion done in a lower-cost setting. Document why the requested site is medically necessary (e.g., first infusion safety, monitoring requirements).
7. Investigational/Experimental
Payer claims insufficient evidence. Cite high-quality RCTs and FDA approval status if applicable.
8. Missing Documentation
Labs, imaging, or prior records weren't included. Send the missing documents with the appeal.
9. Wrong ICD-10 Code
Code didn't support medical necessity. Use the most specific code that matches the indication.
10. Plan Exclusion
Plan excludes the entire category. Verify with employer group; sometimes a riders/exception path exists.