If it comes out of your paychecks pre-tax (meaning before taxes) you can
not deduct it. It has already been deducted from your wages in box 1.
Ask your employer if you're not sure. Otherwise....
Enter it under
Federal Taxes (or Personal for H&B version)
Deductions and Credits
Choose Jump to Full List -or I'll choose what I work on
Then scroll way down to Employment Expenses
Job-Related Expenses - Click the Start or Update button
Then continue to the 3rd screen, it says Enter Your Out-of-Pocket Expenses.
First item is Union and Professional Dues.
But
it is a Misc Deduction and only the amount OVER 2% of your AGI is
deductible so it might not be worth putting it in, unless it's a lot.
And then the total of ALL your itemized deductions has to be more than
the standard deduction to get any benefit.