41 CFR 302-4.202: -4.202 Calculation of maximum per diem rates for the employee and immediate family members while performing PCS travel.

The maximum amount of per diem is calculated as:

(a) For the employee, 100% of the applicable rate.

(b) If the employee and their spouse or domestic partner travel together, the maximum amount the spouse or domestic partner may receive is three-fourths of the employee's daily rate. The employee and their spouse or domestic partner are considered to be traveling together if they travel on the same days along the same general route by using more than one POV.

(c) If the spouse or domestic partner does not travel with the employee but travels unaccompanied at a different time, they will receive the same rate to which the employee is entitled.

(d) Non-spouse immediate family members aged 12 or older receive three-fourths of the employee's rate, and those under 12 receive one-half of the employee's rate.