Parking fees are generally not deductible according to the IRS under publication 463
. They are considered part of commuting expenses to your work, and therefore are not deductible. However, there are several tax preparers who are allowing a portion of parking fees to be deducted.
The argument that certain tax preparers make is that airline crew members do not park from 9 to 5 like a "normal" a business person parks. Airline crew members park for several days in a row, leaving their vehicle overnight beyond the 5 o'clock time period. Therefore, the tax preparers are allowing a 2/3 or 66% deduction of the parking fees.
If you choose to deduct the parking fees, they would be entered on the "Add Yearly Expenses" page for the category, "Only Noncommuting and Nonovernight Parking, Tolls, and Transportation Related Expenses". This will automatically transfer it to line 3, column A of the 2106 form