That’s several weeks earlier than it used to be. It concludes earlier, too, on December 7 this year. (The idea, Medicare officials have said, was to make sure that people who switch plans have their new ID cards by Jan. 1, when the plan changes kick in—something that didn’t always happen under the previous timetable.)

During open enrollment, you can change from one private Medicare Advantage plan to another, or from original Medicare to Medicare Advantage, or from Medicare Advantage back to original Medicare. You can also switch, add, or drop Part D drug coverage.

Judging from the questions I’ve been getting at “Ask Nancy,” people are (understandably) confused by the ever-increasing complexity of the Medicare program. For instance, a lot of people think they have a Medicare supplement (Medigap) plan when they really have a Medicare Advantage plan.

The good news is there’s plenty of consumer-friendly information out there to help you sort things out, and pick a Medicare set-up that works for you.

You can start by looking over our free, downloadable Medicare guide, then moving on to our online Medicare information and our rankings of Medicare HMOs and PPOs.

Medicare itself has all sorts of useful information at its beneficiary website, Medicare.gov, including an interactive plan finder that allows you to find and compare Medicare Advantage and Part D drug plans in your area. If you are already enrolled in Medicare, you should have received your 2012 “Medicare & You” handbook, but if you haven’t, you can download an electronic copy here.

Last but not least, if you have knotty questions about, for instance, what to do if you are on Medicare but still working, your first stop should be Medicare Interactive, a vast yet easy-to-use trove of information maintained by the nonprofit Medicare Rights Center.

Good luck!