- Medicare requires every Part D plan to offer a one-time 30-day transition fill during your first 90 days when a drug you already take isn't covered or is newly restricted.
- The transition fill is a bridge, not a fix — use the 30 days to request a formulary exception or switch to a covered alternative.
- Your plan must send written notice when you use a transition fill, explaining your options and how to request an exception.
You switched Part D plans, filled your usual prescription, and the pharmacist says it isn't covered — or it suddenly needs prior authorization. Do you have to go without your medication while the paperwork gets sorted out? No. Medicare requires every Part D plan to provide a transition fill: a one-time, temporary supply of a drug you were already taking, so you don't face a gap in treatment.
Who qualifies for a transition fill
You qualify when a drug you were already taking is not covered the way you need it under your new plan:
- You just joined a plan. You enrolled in a new Part D plan and it doesn't cover one of your current medications, or covers it only with restrictions such as prior authorization, step therapy, or a quantity limit.
- You switched plans mid-year. The same protection applies when you change plans during the year through a special enrollment period.
- Your plan changed its formulary. At the start of a new plan year, your plan dropped your drug or added new restrictions to it. Continuing members get transition protection in the first 90 days of the new plan year.
- Your level of care changed. Moving between a hospital, a nursing home, and home can trigger transition rights.
The key word is ongoing: transition fills protect medications you were already taking. They don't apply to a brand-new prescription, and they don't cover drugs Part D never covers (for example, most over-the-counter drugs).
What you actually get
During the first 90 days of your plan membership (or the first 90 days of the plan year for continuing members), your plan must cover a one-time supply of up to 30 days at a retail pharmacy — 31 days through a long-term care pharmacy. If your prescription is written for fewer days, refills up to the 30-day total are allowed.
A few details worth knowing:
- It is one fill, not a month of refills. If your doctor writes prescriptions in short batches, the transition policy covers one batch only.
- Cost-sharing still applies. You pay the plan's normal cost-sharing — the transition fill is not free. The amount depends on the tier the plan assigns the drug, and it counts toward your out-of-pocket costs.
- Safety edits still apply. Plans may still enforce quantity limits based on FDA-approved dosing and early-refill rules.
- You get a written notice. When you use a transition fill, the plan must send you a letter within a few business days explaining that the supply is temporary and how to request an exception.
Long-term care residents get stronger protection: the plan must honor transition fills throughout the first 90 days, and after that it must provide an emergency 31-day supply if your exception request is still pending.
What to do during your 30 days
A transition fill buys you about a month. Use it immediately — do not wait until the bottle is nearly empty:
- Call your plan. Confirm the transition fill is on file and ask exactly why the drug is restricted: not on the formulary, prior authorization, step therapy, or a quantity limit. The answer determines your next move.
- Ask your doctor about a covered alternative. Often the simplest fix is switching to a drug your plan prefers — usually a generic in the same class.
- Request a formulary exception if no alternative works. You or your doctor can ask the plan to cover the drug anyway, or to waive the restriction. Your doctor must submit a supporting statement explaining why the alternatives would be less effective or cause harm.
- Appeal if the exception is denied. You can request a redetermination, and further levels of appeal exist. Keep copies of every letter and note the date of every call.
If the exception route looks slow or uncertain, remember the calendar: the Annual Enrollment Period runs October 15 through December 7 each year. Switching to a plan that covers your drug cleanly may be faster than fighting an exception — and checking your drugs on Medicare Plan Finder first prevents the problem from recurring.
Common mistakes to avoid
- Assuming the transition fill renews. It does not. Once the 30 days run out, the drug is uncovered again unless an exception was granted or you switched drugs.
- Waiting to start the exception. Reviews take time, and your doctor's supporting statement can take days to prepare. Start on day one.
- Filling at an out-of-network pharmacy. Transition fills must be filled at a network pharmacy to count.
- Ignoring the plan's letter. That notice starts the clock on your options. File it somewhere you will find it.
How this fits with your 2026 costs
Transition fills count toward your out-of-pocket spending, which matters because in 2026 your total out-of-pocket costs for covered Part D drugs are capped at $2,100 — after that, you pay $0 for covered drugs for the rest of the year. The Medicare Prescription Payment Plan can also spread your drug costs across monthly payments instead of large amounts at the counter.
Bottom line: If a drug you already take isn't covered by your new Part D plan, you are entitled to a one-time 30-day transition fill during your first 90 days — use that window immediately to get an exception or switch to a covered alternative.