The tax code reads that you must be consistent with you application of partial days. If you are constantly getting off Friday at 23:00 you can use... 23 divided by 24, times $59.00 to get the per diem. but on days that you get off at different hours you have to adjust the formula . So days that you get off at 03:00 you would use 3/24 x $59.00. OR you can use 75% each and every time no mater the part of the day... as long as you use whichever formula consistently for the whole year.
It is simpler to use the .75 and probably to your advantage unless you consistently get off at 23:00 on Friday - then the percent of day would be to your advantage. I'll use the .75 as it is easier.
