Prior authorization means your Part D plan must approve a prescription before it will pay for it. If the pharmacy says approval is needed, ask why and contact the prescriber’s office. The plan may need your diagnosis, previous treatment history, or other medical information.

Why Do Plans Use It?

Plans may use prior authorization to:

  • Confirm that a drug is being used for a covered condition
  • Check whether medical criteria are met
  • Encourage use of a preferred alternative
  • Address safety or quantity concerns

Prior authorization is not the same as a prescription. A clinician can prescribe a drug even when the plan has not agreed to cover it.

What Should You Do?

When the pharmacy reports that authorization is required:

  1. Ask the pharmacy for the exact rejection reason.
  2. Contact the prescriber's office promptly.
  3. Ask whether the office will submit the required information.
  4. Check whether a covered alternative is medically appropriate.
  5. Request an expedited, or faster, decision when waiting could seriously harm your health.

Can You Request an Exception?

Yes. You or your prescriber can ask the plan to waive the rule. Your prescriber must explain why the drug is medically necessary despite the plan’s rule. If the plan requires an alternative, the statement should explain why it would be ineffective, harmful, or medically inappropriate.

If the plan denies the request, the notice explains appeal rights and deadlines.

Medicare describes prior authorization and exceptions in its drug-plan rules.

Check the Decision Clock

When you ask a Part D plan to cover a drug, a standard decision generally takes no more than 72 hours. An expedited decision generally takes no more than 24 hours. For an exception, timing depends on when the plan receives your prescriber’s supporting statement. Ask the office where it sent the statement and ask the plan to confirm receipt. These time limits apply to requests for drug benefits. Different deadlines apply to requests to pay you back or to appeals. See CMS’s coverage determination timelines.

Ask the plan for a formal coverage decision, called a coverage determination, and keep any written denial. The pharmacy’s rejection message does not include all the information you need to appeal. If this is a current prescription under new coverage, ask whether you qualify for a temporary supply, called a transition fill.

If you may run out before a decision, tell the prescriber how much medication remains. Ask about an expedited request when waiting could seriously harm your health, and follow the prescriber’s instructions about treatment while the request is pending.

Medicare policy sources last checked: October 8, 2026.