It depends upon whether your payroll deductions are pre-tax or after-tax.
Normally, payroll deductions are pre-tax, because the amount is in box 12 of your W-2 with a code of DD AND because the employer removes that amount from Wages in box 1.
Pre-tax payments for health insurance premiums are not deductible anywhere else, because you already got the tax benefit when they were removed from your wages.
However, occasionally (i.e., much less often), the employer does the payroll deduction as after-tax, in which case, you will be able to deduct these premiums on schedule A (Itemized Deductions) on the federal return.
So, if the premiums are coded with DD in box 12 on your W-2, do not deduct them elsewhere on the return; but if you are not sure if they are pre-tax or after-tax, call your payroll department and ask.
