Q. Do I need to pay taxes for this?
A. No. Reimbursement, from your employer, under an "accountable plan", is not taxable income to you. Reimbursement for business miles actually driven, at less than the IRS rate ($0.625) qualifies as tax free reimbursement. It doesn't matter what the frequency of the reimbursement is.
You report nothing about the reimbursement on your tax return.
