Is this the same taxpayer where you asked to link a W2 to a Sched C to be able to write off expenses:

https://proconnect.intuit.com/community/proconnect-tax-discussions/discussion/is-it-possible-to-link...

Because first, Life Expenses are not part of tax deductions.

Being paid per diem means the person got paid. You cannot also write off something when you are employee being paid for that thing you are incurring. That's the point of per diem.

What you never told us is which part this person is an Employee. If all the time spent working was as the W2 employee, you should stop trying to consider any of it as "business write off" because any other time, unless working as "my own business" means it is personal time and personal life costs.

Giving details in a discussion style always helps. Example:

My taxpayer moved temporarily to Oregon for a job, was paid as W2 employee, for Feb-Aug. He then stay a few more months, but did not work, before returning to his home state of XX. Once back home, he resumed working his own business, which he has done for a couple of years as Sched C filer.