FAQ & plain-English terms
Medicare uses a lot of jargon. Here's what the terms in the drug checker mean. Short answers now; fuller articles are on the way.
Plan types: MA-PD vs PDP
- MA-PD — a Medicare Advantage plan that includes drug coverage. It's an all-in-one plan (medical + drugs) that replaces Original Medicare, usually run by a private insurer. MA-PD plans may also have a separate medical premium that we don't show — the premium in our results is the drug-coverage portion, which is what matters for comparing drug costs. Joining a stand-alone drug plan (PDP) would end this plan and return you to Original Medicare — see below.
- PDP — a stand-alone Prescription Drug Plan you add on top of Original Medicare, just for drug coverage. Your medical coverage stays with Original Medicare. If you have a Medicare Advantage plan, joining one of these ends that plan and returns you to Original Medicare — see below.
Two roads — and why they aren't interchangeable
Almost everyone on Medicare is on one of two roads. They are not two flavors of the same thing, and moving between them is not a drug-only decision:
- Original Medicare — the federal program (Parts A and B) for your medical care. Drug coverage is added separately, with a stand-alone drug plan (PDP). Many people also buy a Medigap policy to help with what Original Medicare doesn't pay.
- Medicare Advantage (MA-PD) — one all-in-one plan from a private insurer that replaces Original Medicare and usually includes drugs. Medigap doesn't work with it.
The part that surprises people
If you have a Medicare Advantage plan and you join a stand-alone drug plan, you are disenrolled from your Medicare Advantage plan and returned to Original Medicare — your medical coverage moves too, not just your drugs. It happens automatically. It is not a way to "add" a cheaper drug plan to a Medicare Advantage plan.
Going back to Original Medicare is a real choice people make on purpose — but it's worth knowing two things first:
- Medigap may not be automatic. You get a one-time 6-month Medigap open enrollment that starts when you're 65 or older and enrolled in Part B. During that window — or when you have a "guaranteed issue right" — an insurer can't use your health history to refuse you or charge you more. Outside those windows, an insurer can consider your health history, and can turn you down or charge more.
- A few plan types work differently. For example, some Private Fee-for-Service (PFFS) plans that don't include drug coverage, and Medical Savings Account (MSA) plans, expect you to add a separate drug plan. A SHIP counselor can confirm which kind you have.
We don't answer whether switching is right for you — that depends on your doctors, your medical costs, and your health history, none of which we see. That's a conversation for a free SHIP counselor or 1-800-MEDICARE.
Mechanics verified against Medicare.gov, July 2026: Switch, drop, or rejoin drug coverage · Get ready to buy a Medigap policy.
Premium, deductible, copay, coinsurance
- Deductible — what you pay out of pocket for drugs each year before the plan starts sharing the cost.
- Copay — a fixed dollar amount per fill (for example, $10).
- Coinsurance — a percentage of the drug's price per fill (for example, 25%) instead of a flat dollar amount. Your dollar cost depends on how much you take, so the checker estimates it as that percentage × the plan's negotiated price per unit × the quantity you set on the drug — set that quantity to match your prescription. If a plan has no published price for the drug, it's left out of the total rather than guessed.
Full article coming soon.
Coverage phases
Medicare Part D cost-sharing changes in phases as your drug spending adds up over the year. Which phase you're in depends on how much you've spent so far — which is personal, so the checker shows the plan's listed cost for each phase, not your live phase.
- Pre-deductible — early in the year, before you've met the plan's deductible. You may pay more (sometimes the full price) here.
- Initial coverage — your regular copay or coinsurance after the deductible is met. This is the headline number in the checker.
- Catastrophic — once your yearly out-of-pocket spending reaches the annual out-of-pocket cap, covered drugs are $0 for the rest of the year. (The old "donut hole" coverage gap was removed in 2025.)
Full article coming soon.
Pharmacy type: standard, preferred, and mail
Where you fill a prescription changes the price on the same plan.
- Standard retail — any in-network pharmacy.
- Preferred retail — specific pharmacies the plan designates as lower-cost. Same drug, often a smaller copay.
- Preferred mail — the plan's mail-order pharmacy. Often the cheapest option, especially for 90-day supplies.
Full article coming soon.
Preferred pharmacies & pharmacy savings
A preferred pharmacy is one a plan has negotiated lower copays with. The same drug on the same plan can cost less at a preferred pharmacy — or by mail — than at a standard one. When the checker finds a real difference, it shows a calm line like “Save about $320/year on this same plan by using one of its preferred pharmacies.”
- Most large pharmacy chains are “preferred” on some plans and “standard” on others. Whether a pharmacy is preferred depends on the plan, not just the pharmacy.
- We compare the pharmacy channels Medicare publishes (standard retail, preferred retail, mail order) at the same days-supply — so the savings reflect only where you fill, not a change in how much you fill at once.
- It’s information, not a re-ranking: plans are still sorted by their everyday (standard-retail) cost, so the order never quietly assumes you’ll change pharmacies.
We can show the savings; your plan’s directory shows which pharmacies qualify. We don’t yet list specific pharmacy names. To find a plan’s preferred pharmacies, check the plan’s website or call 1-800-MEDICARE.
Full article coming soon.
Does filling 90 days at a time save money?
At regular retail pharmacies, usually not — most plans price a 90-day fill at exactly three 30-day copays. Where 90-day fills genuinely save money is through a plan's mail-order pharmacy, and some plans discount them steeply there. When that's true for your medications, the savings line on your results already shows it.
Full article coming soon.
Tiers and the PA / ST / QL flags
Plans sort drugs into tiers (lower tiers usually cost less). Some drugs carry restrictions: PA = prior authorization (the plan must approve it first), ST = step therapy (try a preferred drug first), QL = quantity limit (a cap on how much is covered per fill).
A plan's formulary is its official list of covered drugs. If your drug isn't on it, the checker says "Not covered by this plan's formulary" rather than hiding the plan.
Full article coming soon.