You may already know this, but Flica can do all of your perdiem calculations for taxes for you. I order the service from them every January ($50), and they send back a PDF file containing every trip I took for the year, my perdiem entitlement vs what I was paid, and a summary page detailing how much is due back to me - about $700 to $900 depending how many day trips and overnight trips I worked throughout the year. $50 well spent to avoid the headache of calculating it all myself.