So I can deduct part B from my income?

Part B of what? Are you referring to the Medicare Part B premium on your SSA-1099? If that's what you mean, no, you can't deduct it directly. Just enter it on the screen where you enter your Social Security benefits, and TurboTax will take care of it. Do not enter it again under medical expenses or anywhere else.

The Medicare Part B premium will be included in your medical expenses. Only medical expenses in excess of 7.5% of your Adjusted Gross Income (AGI) are deductible. (Enter the full amount that you paid in TurboTax. TurboTax will subtract 7.5% of your AGI.) In addition, medical expenses are an itemized deduction. They will not reduce your tax or increase your refund unless your total itemized deductions are more than your standard deduction.