Since this reimbursement was not added to your W-2 it sounds like this was an "Accountable Plan"
Employees can be reimbursed in one of two ways.
Accountable Plan: Must meet three requirements:
1. You must have paid or incurred expenses that are deductible while performing services as an employee.
2. You must adequately account to your employer for these expenses within a reasonable time period, and
3. You must return any excess reimbursement or allowance within a reasonable time period.
Non-Accountable Plan:
The payments you receive should be included in the wages shown on your Form W-2. You must report the income and itemize your deductions to deduct these expenses.
Generally, you would report these expenses on form 2106 or 2106-EZ.
