Yes, it is deductible, provided these amounts were not reimbursed to you. That's out-of-pocket money you're paying for medical expenses, so you can claim it as an itemized deduction on Schedule A.
When you're entering your SSA-1099 in TurboTax, you'll see entry boxes for premiums paid for Medicare parts B, C, & D. [edited 4/4/17 4:45pm]
