41 C.F.R. §§ 301-11.19–301-11.22

Except as provided in paragraph (b) of this section, when travel is more than 12 but less than 24 hours, employees receive a per diem allowance of 75 percent of the applicable M&IE rate for each calendar day they are in a travel status. If their travel is 24 hours or more, on the first day of departure and last day of travel, they receive 75 percent of the applicable M&IE rate. Full days of travel are reimbursed at 100 percent of the applicable M&IE rate.

For travel by ship, whether commercial or Government, the agency will determine an appropriate rate within the applicable M&IE rate.

Except as provided in paragraph (c) or (d) of this section, when M&IE per diem is authorized and meals are provided, either by the Government or included in the registration fee, including meals furnished under the authority of chapter 304 of this subtitle, employees must adjust the amount reimbursed by deducting the appropriate amount shown at https://www.gsa.gov/mie.

For meals provided on the day of departure and the last day of travel, employees must deduct the entire allocated meal cost from the decreased M&IE rate. The total amount of meal deductions made will not cause employees to receive less than the amount allowed for incidental expenses.

Employees do not need to deduct meals provided by a common carrier or a complimentary meal provided by a hotel/motel.

Agencies may allow employees to claim the full M&IE amount if the employee was unable to take part in a Government-furnished meal due to the conduct of official business or:

When the agency can determine in advance that lodging and/or meal costs will be lower than the per diem rate, such as when two employees share a room or kitchen facilities are available, reducing the need for buying prepared meals; and

The lowest authorized rate must be stated in the travel authorization before travel or the traveler must be given sufficient notice once travel has begun to adjust spending (i.e., finding and occupying alternative lodging).