2 CFR § 200.475 - Travel costs.
(a) General. Travel costs are the expenses for transportation, lodging, subsistence, and related items incurred by employees who are in travel status on official business of the non-Federal entity. Such costs may be charged on an actual cost basis, on a per diem or mileage basis in lieu of actual costs incurred, or on a combination of the two, provided the method used is applied to an entire trip and not to selected days of the trip, and results in charges consistent with those normally allowed in like circumstances in the non-Federal entity's non-federally-funded activities and in accordance with non-Federal entity's written travel reimbursement policies. Notwithstanding the provisions of § 200.444, travel costs of officials covered by that section are allowable with the prior written approval of the Federal awarding agency or pass-through entity when they are specifically related to the Federal award.
(b) Lodging and subsistence. Costs incurred by employees and officers for travel, including costs of lodging, other subsistence, and incidental expenses, must be considered reasonable and otherwise allowable only to the extent such costs do not exceed charges normally allowed by the non-Federal entity in its regular operations as the result of the non-Federal entity's written travel policy. In addition, if these costs are charged directly to the Federal award documentation must justify that:
(1) Participation of the individual is necessary to the Federal award; and
(1) Temporary dependent care costs (as dependent is defined in 26 U.S.C. 152) above and beyond regular dependent care that directly results from travel to conferences is allowable provided that:
(i) The costs are a direct result of the individual's travel for the Federal award;
(iii) Are only temporary during the travel period.
(d) In the absence of an acceptable, written non-Federal entity policy regarding travel costs, the rates and amounts established under 5 U.S.C. 5701-11, (“Travel and Subsistence Expenses; Mileage Allowances”), or by the Administrator of General Services, or by the President (or his or her designee) pursuant to any provisions of such subchapter must apply to travel under Federal awards (48 CFR 31.205-46(a)).
(e) Commercial air travel.
(1) Airfare costs in excess of the basic least expensive unrestricted accommodations class offered by commercial airlines are unallowable except when such accommodations would:
(i) Require circuitous routing;
(ii) Require travel during unreasonable hours;
(iii) Excessively prolong travel;
(iv) Result in additional costs that would offset the transportation savings; or
(v) Offer accommodations not reasonably adequate for the traveler's medical needs. The non-Federal entity must justify and document these conditions on a case-by-case basis in order for the use of first-class or business-class airfare to be allowable in such cases.
(2) Unless a pattern of avoidance is detected, the Federal Government will generally not question a non-Federal entity's determinations that customary standard airfare or other discount airfare is unavailable for specific trips if the non-Federal entity can demonstrate that such airfare was not available in the specific case.
(f) Air travel by other than commercial carrier. Costs of travel by non-Federal entity-owned, -leased, or -chartered aircraft include the cost of lease, charter, operation (including personnel costs), maintenance, depreciation, insurance, and other related costs. The portion of such costs that exceeds the cost of airfare as provided for in paragraph (d) of this section, is unallowable.