First and foremost, you must itemize.  Because employee expenses are an itemized deduction, if you only take the standard deduction, you will not benefit.  This usually mean that if you do not have other itemized deductions like mortgage interest, you should not use EZPerDiem.

Another important factor would be the type of trips you fly.  If you only fly out-and-back (i.e. day trips) that do not have layovers, those trips will not add to your per diem deduction.  You might still benefit from deducting employee expenses, but not as much as someone with more overnights.

The locations that you stay also play a factor.  Generally, the bigger the cities that you stay in, the more the per diem deduction.  This is because bigger cities generally cost more to stay at, so the per diem rates associated with those cities are higher.

There are some other less common factors that can reduce or eliminate the benefit as well.  If you have a very high income, perhaps the AMT or the 2% limit can reduce your benefit.

The best advice we have is to give it a try.  When you first login, you will be prompted to apply for the money-back guarantee.  This only takes a few minutes, but it should let you know whether or not you will benefit before you spend a lot of time entering data.