Most Medicare decisions are made once. Part D is the one you have to make again every single year, and with Parkinson’s it is the decision that touches you every day, because the prescriptions do not stop.
Our page on Medicare with Parkinson’s covers how Part D sits alongside the other parts. This page is about the drugs themselves — what a plan is allowed to refuse, how to make it change its mind, and the week in January when people run out.
Checked against Medicare’s own pages in August 2026; 2026 figures throughout.
The three stages, and what they cost in 2026
| Stage | What happens | 2026 figures |
|---|---|---|
| Deductible | You pay all out-of-pocket costs until the deductible is met. Some plans have none | No plan’s deductible may exceed $615 |
| Initial coverage | You pay 25% coinsurance on generic and brand-name drugs | Until out-of-pocket spending on covered drugs reaches $2,100 |
| Catastrophic | “You won’t have to pay out-of-pocket for covered Part D drugs for the rest of the calendar year” | Automatic once you hit $2,100 |
Payments made on your behalf — through Extra Help, for instance — count toward the $2,100. So can contributions from a State Pharmaceutical Assistance Program.
The whole thing resets on January 1. If your drugs are expensive, the shape of your year is front-loaded: heavy in winter, free by autumn, heavy again the following January.
Parkinson’s drugs are not protected
Medicare requires every plan to include most drugs in certain protected classes on its formulary. The list is:
- Cancer drugs
- HIV/AIDS drugs
- Antidepressants
- Antipsychotics
- Anticonvulsants
- Immunosuppressants for organ transplants
Read it twice. Levodopa is not there. Dopamine agonists are not there. MAO-B and COMT inhibitors are not there. No Parkinson’s-specific drug class is protected, which means every plan decides for itself which formulations it lists and on which tier.
Three of the protected classes do matter here, and it is worth knowing which. Antidepressants and antipsychotics are protected, which is relevant for depression and for Parkinson’s disease psychosisHallucinations or delusions that can occur in Parkinson's, sometimes as a side effect of medication and sometimes as part of the condition itself.Learn more. Anticonvulsants are protected and are sometimes used for tremor or pain. Your core movement medication is not.
The general floor is thin: each formulary “includes at least 2 drugs in the most commonly prescribed categories and classes, but plans can choose which drugs they’ll offer.” Two drugs in a class is not the same as the specific formulation and release profile that works for you.
Tiers, and the exception that moves a drug down one
Most plans sort drugs into tiers. Medicare’s own illustration:
- Tier 1, lowest copayment — most generic drugs
- Tier 2, medium — preferred brand-name drugs
- Tier 3, higher — non-preferred brand-name drugs
- Specialty tier, highest — very high-cost drugs
If your drug sits in a higher tier and your prescriber thinks you need it rather than a similar drug lower down, you can ask for a tiering exception — “when a drug plan decides to charge a lower amount for a drug that’s on its non-preferred drug tier.”
And if the drug is not on the formulary at all, a plain exception asks the plan to cover it anyway. Either way the mechanism is the same, and this is the sentence to remember: “You or your prescriber must request an exception, and your doctor or other prescriber must provide a supporting statement explaining the medical reason for the exception.”
The supporting statement is the whole request. Without it, nothing happens.
Prior authorization, step therapy, quantity limits — and how to beat each
Plans use three rules to control what they pay for. Each has its own override, and each override needs a specific claim from your prescriber.
Prior authorization. Approval you or your prescriber must obtain before the plan covers a drug. Your prescriber may need to show the drug is medically necessary. To get an exception, the statement must say that because of your medical condition it is medically necessary for you to be on the drug even though you do not meet the plan’s requirements, that you will have negative health effects if you take a different drug, and that a different drug would be less effective.
Step therapy. A form of prior authorization requiring you to try “a certain, less expensive drug on the plan’s drug list that’s been proven effective for most people with your condition” before moving up a step. The exception statement must say that it is medically necessary for you to be on the more expensive drug without trying the cheaper one first, that you will have adverse effects from the cheaper drug, and that it would be less effective. If granted, “your plan will cover the more expensive drug, even if you didn’t try the less expensive drug first.”
Step therapy deserves a moment here. Parkinson’s treatment is individually titrated over years. Being made to walk back down to a drug you already failed on is not a neutral inconvenience — it is a period of worse control, and that is precisely what the exception language is for. Say it in those terms.
Quantity limits. A plan may cover only a set amount over a period — “for example, a plan may only cover 30 tablets of a drug per month.” Someone taking levodopa five times a day will collide with a monthly tablet cap fast. The exception applies “if your prescriber believes that, because of your medical condition, a quantity limit isn’t medically appropriate (for example, your doctor believes you need a higher dose).”
If any request is refused, the decision is appealable. Medicare’s appeals process has five levels, with a decision letter at each explaining how to go further, and your SHIP will help you free of charge.
The January cliff, and the 30-day transition fill
Two facts sit badly together.
Plans change their formularies. A plan “can make changes to its drug list during the year under guidelines set by Medicare” — when therapies change, new drugs are released, or new medical information appears. And plans rewrite formularies wholesale for the new year. Your plan must notify you of changes affecting drugs you take.
You may also switch plans, effective January 1, after Open Enrollment.
Either way you can arrive in January with a medication your plan will not fill. Medicare’s safety net is specific and short:
When your drug coverage begins you may get a transition fill, a one-time, 30-day supply of a drug you’ve been taking that your plan either doesn’t cover or requires prior authorization/step therapy.
One time. Thirty days. That is a window to get an exception filed, not a solution. If a pharmacy tells you in early January that this is a transition fill, treat it as a deadline: contact the plan and your prescriber that week.
Two related traps. Your coinsurance can rise mid-year “when the manufacturer raises the price,” and also if you stay on a brand-name drug after the plan adds a generic and moves the brand to a higher tier. Neither requires a new plan year to happen.
Ways to pay less
Extra Help. The largest single lever if your income is limited. In 2026 the limits are $23,940 in income and $18,090 in resources for an individual, $32,460 and $36,100 for a married couple. If you qualify: $0 premium, $0 deductible, and no more than $5.10 for a generic or $12.65 for a brand-name drug. People with full Medicaid, an SSI payment or a Medicare Savings Program get it automatically; everyone else applies through Social Security, and there is no Part D late enrollment penalty while you have it.
LI NET. If you qualify for Extra Help or Medicaid but are not yet in a drug plan, the Limited Income Newly Eligible Transition program gives temporary Part D coverage. It “covers all Part D covered drugs, and there are no network pharmacy restrictions.”
State Pharmaceutical Assistance Programs. Some states help with plan premiums or cost sharing, and “SPAP contributions may count toward your Medicare drug coverage out-of-pocket limit” — which means they can also move you toward the $2,100 cap faster.
Manufacturer assistance programs. Some pharmaceutical companies run their own assistance programs — Medicare calls them Pharmaceutical Assistance Programs — for people enrolled in Part D. Eligibility differs by company, and Medicare hosts a lookup for the drugs you take.
Medicaid, if you qualify, and a Medicare Savings Program, which brings Extra Help with it.
The Medicare Prescription Payment Plan. All plans offer it, participation is voluntary and there is no cost to join. Instead of paying the pharmacy, you get a monthly bill from your plan that spreads your out-of-pocket drug costs across the calendar year. Medicare is careful to say what it is not: it “might help you manage your monthly expenses, but it doesn’t save you money or lower your drug costs.” For someone facing a $600 January and nothing in October, that smoothing is the point.
The penalty that never goes away
Skip Part D when first eligible and go 63 or more days in a row without creditable drug coverage, and a penalty is “permanently added” to your premium.
The arithmetic: 1% of the national base beneficiary premium — $38.99 in 2026 — times the number of full uncovered months, rounded to the nearest 10 cents, added every month. Medicare’s own example: wait 14 months and you pay a 14% penalty. It follows you when you switch plans, the base premium rises most years, and you pay it for as long as you have Part D.
The exception, again, is Extra Help: with it, you do not pay the penalty.
An hour every October
If this applies to you
| Your situation | What to do |
|---|---|
| Choosing a Part D plan | Compare on your exact drug list, not the premium. Parkinson’s drugs are not in a protected class, so formularies genuinely differ |
| Your drug is on a high tier | Ask for a tiering exception. Your prescriber must supply a supporting statement giving the medical reason |
| Plan wants you to try a cheaper drug first | Request a step therapy exception. Say plainly that a period of worse control is an adverse health effect |
| Plan only covers 30 tablets a month | Quantity limits have their own exception where the limit is not medically appropriate for your dose |
| Pharmacy says “transition fill” in January | One fill, 30 days. File the exception this week — that is what the window is for |
| Costs are all in the first months of the year | The Medicare Prescription Payment Plan spreads them across the year at no cost. It does not reduce them |
| Income under about $24,000 | Apply for Extra Help. $0 premium, $0 deductible, a few dollars per prescription, and no late enrollment penalty |
| On Medicaid or Extra Help but not yet in a plan | Ask about LI NET — temporary Part D coverage with no pharmacy network restrictions |
| Never signed up for Part D | The penalty is permanent and grows with each uncovered month. Enrol at the next opportunity rather than waiting further |
| Refused an exception | Appeal. There are five levels, and your SHIP will work through it with you free of charge |
This page explains Medicare’s national Part D rules. Formularies, tiers and costs are set by individual plans and change every year. Check your own plan’s documents, and confirm anything that matters with 1-800-MEDICARE or a SHIP counselor.