There may be consequences if you don't enroll in Part D when you are first eligible. You'll likely have to pay a higher premium if you decide to join later.

This penalty won't be charged if you had drug coverage from another place, such as an employer. However, the coverage you had must have been as good as a standard Medicare prescription plan. This is called creditable prescription drug coverage.

Even if you dropped or lost that coverage, you can avoid the penalty as long as you haven't been without coverage for more than 63 days in a row. You won't be charged a penalty if you get Extra Help.

The amount of the penalty depends on how long you went without Medicare drug coverage or other similar prescription drug coverage. The penalty is calculated by multiplying 1% of the national average monthly premium by the number of months you weren't covered. That amount is rounded to the nearest $0.10, then added to your monthly premium. You will typically need to pay the penalty every month while you have Medicare drug coverage. Since the national average premium can go up each year, the penalty can also go up every year.

It's important to keep this penalty in mind when deciding whether to enroll in a plan. This is true even if you have low prescription drug costs now. If you wait too long, you'll pay a larger penalty when you need more help with prescription costs.