There is nothing that requires you to enroll in a Part D prescription drug plan when you become eligible for Medicare. However, suppose you do not enroll when you first become eligible. In that case, even if you don’t take any prescription drugs, you will be assessed a Part D late enrollment penalty when you eventually enroll in a Part D plan.
The penalty is assessed if you don’t have Part D coverage or other creditable prescription drug coverage for 63 or more days in a row after you become eligible for Medicare.
How much the Part D late enrollment penalty is will depend on how long you did not have Part D or creditable prescription drug coverage. The penalty is calculated by multiplying 1% of the “national base beneficiary premium” ($33.06 in 2021) times the number of full, uncovered months you did not have Part D or creditable coverage.
If you don’t take any prescription drugs and do not enroll in a Part D plan for several years after becoming eligible for Medicare, the Part D penalty can be a significant amount of money, and once assessed, it never goes away. There are many Part D plans with low or even $0 premiums(for some MAPD plans), so you would be wise to enroll in one even if you do not take any prescription drugs to avoid what could be a costly penalty down the road.