Reason Codes U5565 and U5566 occur when the admission date submitted on a hospice claim does not match the beneficiary's hospice election period start date. Effective April 1, 2026, these edits help prevent overpayments and claim errors. Providers should verify eligibility records, correct discrepancies, and resubmit claims to ensure timely Medicare reimbursement. https://rotbilling.com/understanding-reason-codes-u5565-and-u5566-for-hospice-claims/