No. Joining a Medicare drug plan is your choice. However, if you don’t join a plan from October 15th through December 7th of each year, and you don’t currently have a drug plan that, on average, covers at least as much as standard Medicare prescription drug coverage, you will have to wait until October 15th of the following year to join.
When you do join,
your premium cost will go up at least 1% per month for every month that you wait to join.
Like other insurance, you will have to pay this penalty as long as you have Medicare prescription drug coverage.
(Source: U.S. Department of Health & Human Services)