The official source for the federal government per diem rates allowable for expense reimbursement in business travel away from home within the continental United States (CONUS) is the online information on the U.S. General Services Administration webpage http://www.gsa.gov/portal/category/21287. On this webpage, you can also find links to the Department of Defense per diem rates for areas outside the continental United States (OCONUS), such as Alaska, Hawaii, Puerto Rico and U.S. possessions, and the State Department’s foreign per diem rates. The IRS recently announced that it is no longer issuing Publication 1542, Per Diem Rates, which had been available as an all-electronic publication in which IRS reproduced the GSA rates with additional information. The print publication of Publication 1542 ceased several years ago.
The federal per diem rates are accepted in lieu of actual receipts for business travel reimbursement under the accountable plan rules of the tax regulations at §1.62. An accountable plan must satisfy three rules: that the expenses reimbursed were deductible expenses incurred for the business; expenses are adequately accounted for within a reasonable period of time (with documentation of the business purpose, and receipts, but receipts are not required for expenses to which the per diem rules apply if the business has chosen to reimburse those travel expenses using the per diem rules); and any amount in excess of the documented expenses must be returned to the business within a reasonable period of time.
Even if you use the per diem rates, employees still must keep and turn in records to prove the time, place and business purpose of their travel as well as mileage. Contractors can only use the meals & incidental expenses (M&IE) method and must submit receipts for lodging. If expense reimbursements to employees or contractors are not substantiated, such payments do not qualify as tax-exempt reimbursements and, instead, must be included and reported on Forms W-2 or 1099 as part of the gross income paid to the employee or contractor. For travel away from home for business purposes, original receipts serve as substantiation for lodging, meal and incidental expenses; or, the per diem allowance rates (a lump sum to cover each day) may be used as acceptable substantiation under the rules explained in Rev. Proc. 2011-47. Original receipts or the federal per diem rates are also necessary for organizations to take allowable business expense deductions on their business tax returns.