An expense is personal if it cannot pass something called we'll refer to as the "what if" test. Ask yourself: "What if I didn't have this job? Would I still incur the expense?" An item may seem, at initial glance, to be a legitimate itemized deduction, but if it cannot pass the "what if" test above, then it is not allowed to be written off as an airline-related tax deduction on IRS Form 2106. EXAMPLE (Haircuts or socks'): One could argue that haircuts and socks are ordinary and necessary, but they do not pass the "what if" test above. They are therefore considered a personal expense rather than a legitimate employee business expense and cannot be deducted.