I'm considering a job in CA but it is unlikely that I will relocate my family while I work on the west coast. How would per diem be structured if the position is a "permanent" one and how do CA taxes get calculated? I'm not looking to "cheat" the system, but I am looking for the legal ways to minimize the tax hit and the overall expense hit of having to maintain a hotel / apartment in CA while the family is in TX.

You can possibly claim your per diem costs for up to one year if you honestly expect the job assignment to terminate in less than one year.

However, if you KNOW the job will be lasting more than one year, then you CANNOT deduct your per diem expenses for that year. The decision to NOT move your famly is a personal one that is not driven by business considerations.

The travel expenses (per diem costs) is itemized deduction and only the expenses that are more than 2% of you AGI are deductible. Read: Your U.S. Tax Return: Itemized Deductions