If you are on Medicare, you do not have to complete Form 8962. That is for health plans purchased through the Marketplace. If you have a marketplace plan you would have received Form1095-A. If you receive that Form you enter it into TurboTax.
If you had Medicare all year:
Click on the tab Health
Insurance at the top, answer "I
had health insurance coverage all year" on the 1st
screen.
Answer "NO" to
the questions on the next screen about coverage through the ACA.
Enter your Social Security benefits from your SSA-1099 into TurboTax:
https://ttlc.intuit.com/replies/4767455