Most Medicare Part D plans charge a monthly premium that varies by plan carrier. If you are enrolled in an Medicare Advantage Plan, or a Medicare Cost Plan that includes Medicare prescription drug coverage, your prescription drug coverage will most likely be included in your monthly premium, and in some Part C plans, there will not be a premium.
Since the monthly Part D premium is set by the individual insurance company, premiums will vary based on several different factors including the insurance carrier, where you live, the drug formulary, etc. Most plans vary from $10 – $100 depending on the factors mentioned previously, but the projected national average monthly premium in 2021 is $33 for a Part D drug plan (according to cms.gov)
If you have a high income you may pay an extra amount on top of your standard plan premium. Just like with Part B of Medicare, in 2021, if you make over $88,000 as an individual or over $176,000 if you file your taxes jointly then you will pay an Income Related Monthly Adjustment Amount also called an IRMAA. Below is a chart that will tell you the extra amount you may have to pay based on your income.
In 2021, the annual for Part D deductible is $445. Keep in mind, this is the max deductible amount insurance carriers can charge you. Companies may charge the full deductible, a partial deductible, or waive the deductible entirely. You will pay the network discounted price for your medications until you have satisfied the deductible. After that, you enter the Initial Coverage Phase.