You would need to ask the accountant if it is being taxed or not (or decipher it based on your pay stubs).
If it is just being lump with your regular wages and not a separate item, it is probably taxable. In that case, you could HYPOTHETICALLY deduct your business expenses on your tax return. However, due to limitations and restrictions, unless the expenses are large, those deductions are likely not going to change your taxes. Also, the proposed tax reform would eliminate that deduction.
However, it likely it is still being treated as a non-taxable reimbursement ("accountable plan"), as that not only saves you money, it also saves the employer money.
But again, asking the accountant/payroll would probably be the easiest way to figure out how it is being handled.
