If you want to save a bundle on Medicare next year, take some time this summer to prepare.

Open enrollment for Medicare Advantage and Part D prescription drug coverage runs each year from Oct. 15 to Dec.7. It's a critical period for retirees because this is generally the one time when they may make changes to their coverage.

The options include switching from original Medicare, which is known as Part A hospital insurance and Part B medical coverage, to a private Medicare Advantage plan, which provides additional services.

During open enrollment, you may also join a prescription drug plan, opt to drop coverage for drugs altogether, or swap from one Medicare Advantage plan to another.

Enrollees can also choose to stick with their current selection.