Sources: CMS DMEPOS Required Prior Authorization List (updated 29 July 2026); CMS fact sheets for CMS-4201-F and CMS-0057-F, checked 13 October 2026. Your plan’s Evidence of Coverage has its own list.
Original Medicare vs Medicare Advantage
| Topic | Original Medicare | Medicare Advantage |
|---|---|---|
| Prior authorization for CPAP or oxygen | Not on CMS’s Required Prior Authorization List | Plan may require it |
| Coverage criteria | NCDs and LCDs | Must follow NCDs, LCDs and Traditional Medicare rules (CMS-4201-F) |
| Purpose of prior authorization | Not applicable | Coordinated care plans: only to confirm diagnosis or medical criteria, or medical necessity |
| Switching plans mid-treatment | Not applicable | At least 90 days without new prior authorization for an active course of treatment |
| Decision time | Not applicable | 72 hours expedited, 7 calendar days standard (CMS-0057-F, generally from 1 Jan 2026) |
| Denial reason | Not applicable | Specific reason required from 2026 |
| Approval length | Not applicable | Valid as long as medically reasonable and necessary for the course of treatment |
What this means for CPAP users
Because MA plans must follow Medicare’s CPAP rules, prior authorization shouldn’t add criteria beyond the LCD (Medicare CPAP rules). If you’re denied, ask for the specific reason, check it against the LCD, and use your plan’s appeal process.
Verdict
Prior authorization is mainly a Medicare Advantage issue for CPAP and oxygen. Know the 2026 timeframes, ask for the denial reason in writing, and compare it with Medicare’s own criteria.
Related: Medicare Advantage vs Original Medicare for DME, Medicare oxygen coverage, appealing a DME denial.
See also: appealing a Medicare Advantage denial.