41 CFR § 301-13.2 - Allowable additional travel expenses for special needs.
The agency approving official may pay expenses deemed necessary by the agency to reasonably accommodate a special need, including:
(a) Transportation and per diem expenses for an immediate family member or attendant required to accompany the employee;
(b) Specialized transportation to, from, and at the temporary duty location;
(c) Specialized services from a common carrier to accommodate the special need;
(d) Baggage handling costs directly resulting from the special need;
(e) Renting and transporting a wheelchair;
(f) Other than coach class accommodations to accommodate the special need; and
(g) Services of an attendant when necessary to accommodate the special need.
For limits on attendant payments beyond travel expenses, refer to 5 U.S.C. 3102 and guidance available at https://www.opm.gov/FAQs.