After March 31, 2007, you will be locked in to the Medicare plan you are in until the next Open Enrollment period (Nov. 2007). In the past, Medicare beneficiaries could switch plans once a month. Some of the managed care plans (Medicare Part C) offer more benefits and lower premiums. Beneficiaries sometimes found themselves in a plan that didn't fit their needs.
Now if that happens, you won't be able to switch once you are locked in to your plan for 2007. So be sure to investigate and compare plans to be sure you have the one that fits your needs. For married couples, you need to be aware that you could possibly choose a different plan for each of you depending upon your particular health care needs.
You can find information on plans ofered in your geographic area by visiting the Medicare website. Be sure that the plan you choose is one that your physician accepts, or you will have to switch physicians.