Can the cost of my prescriptions change while I am still in my Medicare Part D plan's Initial Coverage Phase?

Yes. If your Medicare Part D prescription drug plan cost-sharing is based on a percentage of retail price (such as 25% coinsurance), you will find your coverage cost can increase (or decrease) due to the changes in your drug’s retail price – even if you always use the same pharmacy (although in recent years, retail drug pricing has become a bit more stable for many drugs).

For example, if you are in your plan's Initial Coverage phase - and your cost-sharing is 25% coinsurance - and your formulary medication has a retail price of $400 in January, then you will pay $100 for cost-sharing when purchasing your medication (25% of $400).

If the retail drug price increases to $450 in March, you would pay $113 for the same prescription (25% of $450).

Please remember that your plan's negotiated retail drug prices can vary over time, between network pharmacies (preferred and standard pharmacies) -- and even between preferred network pharmacies.

Question: Where can I learn more about my Medicare Part D plan's cost sharing and retail drug information?

(1) You can telephone your Medicare Part D plan's Member Services department using the toll-free telephone number found on your Member ID card.

(2) You can telephone a Medicare representative at 1-800-Medicare (1-800-633-4227) and ask for an estimated retail drug price at your chosen pharmacy.

(3) You can use our the drug finder Drug Finder ( on this site) to see how all Medicare Part D prescription drug plans (or Medicare Advantage plans that include drug coverage (MAPDs)) in your area cover a specific drug. We include the cost-sharing (copays or coinsurance percentage) along with average retail drug cost (when available).

In the following example, we show the coverage for ADVAIR DISKUS MIS 250/50 across all 2023 Florida Medicare Part D plans cover this medication. You can see in the screenshot below that the first Florida Part D plan has coinsurance of 25% of retail and the next plan has a copay of $44, and so on. The estimated average retail cost at this specific time is $424.20* (averaged across all network pharmacies in Florida). So, the coverage for this drug is 25% of $424.20 or around $106 (with the actual cost possibly varying at different pharmacies). You can repeat the search using on this site to see any changes in the average retail drug cost that would affect the cost-sharing or coverage cost.

Drug Finder Q1Rx.com chart showing cost-sharing and retail drug prices

You can click on the average retail drug price in the right column to see a retail price history for this medication. And, if you click on the cost-sharing, you will see the cost-sharing for all types of pharmacies across all phases of coverage.

Currently, no stand-alone Prescription Drug plans cover ADVAIR DISKUS MIS 250/50; however, they do cover the generic FLUTICASONE-SALMETEROL 250-50 INHALER [Advair]

* Using the estimated retail drug costs as of 07/14/2023