I am not drawing Social Security, In the year of completing a 401K to Roth conversion, I understand that federal taxes are due but will the other FICA taxes ( Social Security & medicare) also be applied ?

Hi,

Not to the best of my knowledge. Social Security/Medicare (aka FICA) taxes are assessed in the year in which earnings are paid, even if income taxes are deferred on the earnings because you put them into a 401K or IRA. That said, though, my expertise is limited to Social Security taxes and not tax regulations, so you should probably double check with the IRS.

Best, Jerry