If your spouse or domestic partner does not accompany you but travels unaccompanied at a different time, he/she will receive the same per diem rate to which you are entitled.
Code of Federal Regulations
[FTR Amdt. 98, 66 FR 58196, Nov. 20, 2001, as amended by FTR Amdt. 2010-06, 75 FR 67631, Nov. 3, 2010]