When you get covered under, say, an MSA policy with Medicare, it does not actually cover prescription medication. That’s what Medicare Part D is for.

In the simplest language possible, Medicare Part D is a government program to help policy holders cover the costs of prescription medication.

Whether going through Aetna or otherwise, there are essentially two different ways to get your prescription needs covered through Medicare. These are the Medicare Prescription Drug Plan, and the Medicare Advantage Plan.

With the Medicare Prescription Drug Plan, or the MPDP, you are adding drug coverage to a regular Medicare program. In other words, if you’re not insured through Medicare, you cannot get MPDP coverage until you switch to a Medicare provider. This is the part of Medicare referred to as “Part D.”

The Medicare Advantage Plan is actually covered under Part C, which is similar but different

Aetna offers plans through both the MPDP and the Medicare Advantage Plan, so you have your choice of either one if you are going through Aetna for your Medicare policy, but for the purpose of this piece, we’re primarily discussing MPDP, or Part D.

When you add other insurance policies and social services to the mix, things can get a little complicated. Depending on whether you have Medicaid, COBRA, food stamps, etc., you may wind up paying more or less out of your own pocket for drugs and other related expenses.

For instance, if you have Medicaid, Part D should cover the entirety of your drug expenses. If you have COBRA, then it may be smarter to look into Medicare Part B. TRICARE recipients are likewise recommended to look into Medicare Part B. In short, Medicare Part D isn’t for everyone, although it can be very useful if you are eligible.

Note that there are some risks involved in joining the MPDP. For instance, if you have a spouse who is covered by union or employer insurance, or if you are, then you may well lose that coverage the minute you sign up for MPDP. You’ll want to weigh your options and consider whether you’d be willing to give up your current coverage in order to reap the benefits of the MPDP before making the switch.

MPDP or Part D may or may not be your best bet for getting good prescription drug insurance coverage. Make sure to look at all of your options before making a decision.