You can deduct your health insurance premiums paid after tax, you cannot deduct pre tax premiums.
To enter your medical /insurance expenses -
- Click on Federal Taxes (Personal using Home and Business)
- Click on Deductions and Credits
- Click on I'll choose what I work on (if shown)
- Scroll down to Medical
- On Medical Expenses, click the start or update button
See How much did you spend on insurance premiums? page