I was an employee for part of the year and paid health insurance premiums. Then i became self-employed, and paid $0 for a state medicare plan. Can i deduct the premiums?

I was an employee for part of the year and paid health insurance premiums. Then i became self-employed, and paid $0 for a state medicare plan. Can i deduct the premiums? My guess would be that i can only deduct premiums that i paid during the period of time when i was self-employed.