I am a retired Federal employee and stayed on the Federal Employee Health Benefits Plan. Are the premiums deductible?

Whether you can deduct your medical insurance premiums in a way that lowers your taxes depends on a couple of factors. 

Firstly, whether you itemize deductions or use the standard deduction. Your total itemized deductions must exceed the Standard Deduction for your medical expenses to make a difference in what you owe.

Secondly, even if you itemize, your deductions for medical expenses, including health insurance premiums, are subject to a 7.5% AGI “threshold”.  In other words, they only “count” to the extent they exceed 7.5% of your adjusted gross income (AGI). 

Enter your health insurance premiums in the TurboTax section Federal>>Deductions & Credits>>Medical>>Medical Expenses.