Do I put down my cost for Medicare D premiums even if it does not come directly from my benefit?

you can enter the Part D premiums through the SSA-1099 since the amount will carry to the medical expense section of schedule A or enter directly in the medical expense section. Just don't enter the amount twice. 

If you pay out of pocket for Part D, you can enter that amount as a medical expense.

If you receive Social Security benefits, your Medicare is deducted from your SS.   When you enter the SSA1099 for your Social Security, the amount paid for Medicare flows automatically to the medical expense section of the software, so do not enter it again.

MEDICAL EXPENSES

The medical expense deduction has to meet a rather large threshold before it can affect your return. The amount of medical (including dental, vision, etc.)  expenses that will count toward itemization is the amount that is OVER 7.5% of your adjusted gross income. You should only enter the amount that you paid in 2024—do not include any amounts that were covered by insurance or that are still outstanding.  Of course, your medical expenses plus your other itemized deductions still have to exceed your standard deduction before you will see a difference in your tax due or refund.

To enter your medical expenses go to Federal>Deductions and Credits>Medical>Medical Expenses

2024 STANDARD DEDUCTION AMOUNTS

SINGLE $14,600    (65 or older/legally blind + $1950)

MARRIED FILING SEPARATELY $14,600    (65 or older/legally blind + $1550)

MARRIED FILING JOINTLY $29,200    (65 or older/legally blind + $1550)

HEAD OF HOUSEHOLD $21,900    (65 or older/legally blind + $1950)