Once you choose a Medicare drug plan, here’s how you may be able to join:

  • Enroll on the Medicare Plan Finder or on the plan’s website.
  • Complete a paper enrollment form.
  • Call the plan.
  • Call 1-800-MEDICARE (1-800-633-4227).

When you join a Medicare drug plan, you’ll give your Medicare number and the date your Part A and/or Part B coverage started. This information is on your Medicare card.
Joining a Medicare drug plan may affect your Medicare Advantage Plan
If your Medicare Advantage Plan (Part C) includes prescription drug coverage and you join a Medicare Prescription Drug Plan (Part D), you’ll be dis-enrolled from your Medicare Advantage Plan and returned to Original Medicare.

Most Medicare Prescription Drug Plans charge a monthly fee that varies by plan. You pay this in addition to the Medicare Part B premium. If you belong to a Medicare Advantage Plan (Part C) or a Medicare Cost Plan that includes Medicare prescription drug coverage, the monthly premium you pay to your plan may include an amount for drug coverage.
Deductibles vary between Medicare drug plans. No Medicare drug plan may have a deductible more than $320 in 2012. Some Medicare drug plans don’t have a deductible.

Co-payment, or coinsurance, is the amount you pay for each of your prescriptions after you have paid the deductible (if your plan has one). Some Medicare Prescription Drug Plans have different levels or “tiers” of co-payments or coinsurance, with different costs for different types of drugs.

Complete Medicare information at the official U.S. government Medicare site