Medicare Prior Authorization for Imaging: Phone, Portal, Forms

Original Medicare has no prior authorization program for outpatient imaging. Claims are paid or denied against national and local coverage determinations after the service.

What to know

• The CMS prior authorization programs cover specific items such as certain hospital outpatient department services and durable medical equipment; outpatient MRI, CT and PET are not on that list.
• Coverage for a study depends on the national coverage determination for the modality and any local coverage determination from the Medicare contractor for the state.
• Medicare Advantage plans are run by private insurers and do set their own prior authorization rules; check the plan.

Checked against cms.gov on September 29, 2026. Plans change their vendors and phone numbers; if something here is out of date, tell us.