There are late enrollment penalties for both Medicare Part D and A, according to Medicare.gov. Recipients ordinarily eligible for premium-free Medicare Part A who fail to buy the plan when they first become eligible may pay up to 10 percent more for coverage for the first four years of coverage.
Similarly, a recipient who goes without Part D prescription drug coverage for 63 days or more pays a penalty along with his monthly Medicare Part D premium, notes Medicare.gov. The cost depends on the length of coverage lapse. Medicare calculates the penalty by multiplying 1 percent of the national base premium by the number of uncovered months. For 2015, the national base premium is $33.13.