The enrollment period begins this Wednesday and runs through the end of the year (November 15 - December 31, 2006).
First-time enrollments and plan switching take place during the next 6 weeks. If you're satisfied with your current plan, you need take no action - your plan will continue into 2007. Although, since plans are expected to change their list of covered drugs and other benefits, it's a good idea to review your options for 2007.
How do you do that?
Go to medicare.gov and select "Compare Medicare Prescription Drug Plans". That will take you to Medicare's Drug Plan Finder which will help you compare and select the best plan based on cost and coverage. Changes you make will take effect on January 1, 2007.
If you're Medicare eligible and not currently enrolled, keep in mind:
[Some] people will have to pay a penalty for every month they were eligible to join a Medicare drug plan and weren’t enrolled in one. They will have to pay this penalty in addition to their monthly premium for as long as they are enrolled in a Medicare drug plan.
The late enrollment penalty amount is at least 1% of the "base beneficiary premium" (the national average premium) for each full uncovered month that someone was eligible to join a Medicare drug plan and didn’t.
- Calculating the Late Enrollment Penalty, Centers for Medicare and Medicaid Services (CMS)
Here's an example from CMS's Tip Sheet on enrollment penalties:
Mrs. Jones is currently eligible for Medicare and was eligible to join a Medicare prescription drug plan until May 15, 2006. She doesn’t have prescription drug coverage from any other source. She didn’t enroll by May 15, 2006, and instead enrolls when she is next eligible to join, from November 15 – December 31, 2006. Her drug coverage is effective January 1, 2007. Since Mrs. Jones is without creditable drug coverage from June through December 2006, her penalty will be 7% (or 1% for each of the 7 months from June through December) of $27.35 or $1.91. She will pay $1.91 each month in addition to her plan’s monthly premium in 2007.
Two government sites full of good info:
Medicare's Frequently Asked Questions
Centers for Medicare and Medicaid Services (CMS)