Employer reimbursements per diem, Box14

[rich]

I had a client who has tax home in IL and on temporary job assignment working in MO and his W2 shows Box 14 per diem $37840.He stayed in MO renting apartment and visit every weekend to Illinois. Do I had to file 2106 and if he is paid by per diem by employer and account for the reimbursements?

Thanks in advance.