Possibly. If you itemize deductions, you may claim out-of-pocket (after-tax) medical insurance premiums, such as supplemental Medicare insurance premiums, as a medical expense. The deduction is limited to the amount of medical expenses that exceeds 7.5% of your adjusted gross income (AGI).
There is a screen in the medical expenses section of TurboTax just for insurance premiums. Note that you should not enter medical insurance premiums reported elsewhere, such as Medicare Part B, C, or D premiums reported on Form SSA-1099. (Click the screenshot below to enlarge it for reference.)
To enter out-of-pocket medical insurance premiums:
Note: If using the TurboTax CD/Download software, you'll use the Find function and the "Jump to" link (instead of "Tax Tools") to search for the topic.