The IRS permits taxpayers to use general predefined rates to substantiate business expenses under Internal Revenue Code Sec. 274(d) for lodging, meals, and incidental expenses incurred while traveling away from home for business purposes.
The General Services Administration (GSA) released the federal domestic per diem rates for periods effective from 10/1/17 through 9/30/18 (aka fiscal year 2018).
The maximum standard per diem rate has increased from $142 to $144 and is generally made up of $93 for lodging and $51 for meals and incidental expenses.
Per diem rates for localities without standard rates range from $144 to $498 so be sure to download rates here in excel format.
Be sure to save all receipts!