If you are reimbursed under an accountable plan, then reimbursements may be tax free. For example, if reimbursements for your mileage exceed the IRS standard mileage rate, then only amounts up to the rate are tax free; excess reimbursements are taxable.
Items directly reducing income. Personal deductions such as for mortgage interest, state and local taxes, and charitable contributions are allowed only if deductions are itemized on Schedule A, but deductions such as for alimony, capital losses, moving expenses to a new job location, business losses, student loan interest, and IRA and Keogh deductions are deducted from gross income even if itemized deductions are not claimed.