There are two types of Part D plans:
Stand-alone Prescription Drug Plans (PDPs): “Stand-alone” plans offer prescription drug coverage only. If you sign up for one of these, you continue to get all your other medical services, such as doctor visits and hospital stays, through the Original Medicare program or through some Private Fee-for-Service (PFFS) plans if they do not offer drug coverage.
Medicare Advantage Plans (MA): “MA” plans are private health plans such as Health Maintenance Organizations or HMOs, Preferred Provider Organizations or PPOs, and Private Fee-for-Service or PFFS plans. If you sign up for one of these managed care plans to get drug coverage, be aware that you will be required to leave the Original Medicare program.
All your medical expenses will be covered by the new plan. Before joining a private plan, it is important to make sure that your health care providers are included in the plan’s network and to examine the copayments the plan will require for all the services you need. Many of these plans offer low premiums and deductibles, but charge high copayments for certain kinds of services.
If you are in a Medicare cost program or a PFFS plan that does not offer drug coverage, you can enroll in a stand-alone prescription drug plan. In most cases, if you are in an HMO or PPO, you must receive your entire medical and drug coverage through that plan. You cannot enroll in a separate stand-alone plan.
There are a number of national stand-alone plans, and dozens of local or regional plans, both stand-alone and managed care. The number of choices you have depends on how many plans are approved to offer the drug benefit where you live.