I'm assuming you don't own your own business...or you would be writing it off. IF you w-2 somwhere, unless you spend alot on meals/entertainment...it's nto even worh the hassle of writing off as you probaaly wont' exceed the threshold ( that's assuming you itemize now)
As far as proof...you dont' need anythiing unless you get audited, lol. there are guidlines as to what you need online. simple stuff, reciept and business purpose.
Just claim a bit mroe on charitable contributions this year
it's alot easier and will help you out a bit more.