Medicare Part A, B, and D are all subject to a late enrollment penalty. The penalty amount is added to your premium for missing your initial sign up window.[1][2]

In most cases, you won’t have to pay these penalties as long as you meet certain conditions. For example, having a creditable employer health plan and creditable prescription drug coverage will in most cases allow you to delay both Part B and D while you are working and then enroll during an 8 month Special Enrollment period after you stop working for no late fee.

Part A Late Enrollment Penalty: If you don’t automatically qualify for Part A (and therefore don’t qualify for Part A for free), for example, if you haven’t worked and paid Medicare taxes long enough, you’ll have to sign up for Part A during your initial enrollment period during the 7 months surrounding your 65th birthday. If you don’t sign up during initial enrollment, you’ll owe a penalty on your Part A premium.

Part B Late Enrollment Penalty: Your monthly premium for Part B may go up 10% of the standard premium for each full 12-month period that you could have had Part B, but didn’t sign up for it. Also, you may have to wait until the General Enrollment Period (from January 1 to March 31) to enroll in Part B. Coverage will start July 1 of that year.

Part D Late Enrollment Penalty: You may owe a late enrollment penalty if, for any continuous period of 63 days or more after your Initial Enrollment Period is over, you go without PartD, a Part C plan that offers a drug plan, or creditable prescription drug coverage. Medicare calculates the penalty by multiplying 1% of the “national base beneficiary premium” ($33.06 in 2021) times the number of full, uncovered months you didn’t have Part D or creditable coverage. The monthly premium is rounded to the nearest $.10 and added to your monthly Part D premium.


  1. Part B late enrollment penalty. Medicare.Gov.
  2. Part D late enrollment penalty. Medicare.Gov.