Medicare Part D plans can only be purchased through private companies. Between November 15th and December 31st each year is the Annual Election Period which allows you to sign up for the first time if you have put off purchasing a plan or change plans if there is another one you prefer. One of the best resources for finding the plan that best meets your needs is on the Medicare website (www.medicare.gov). On the website, you can go in and enter your RXs and the website will rank the plans for you based on cost providing you with very detailed information like premiums, copayments, what kind of cost you should expect each month, contact information, etc.
Medicare Part D is saving some seniors hundreds and others thousands of dollars each year. Make sure you take advantage of the opportunity.