Legal Question in Real Estate Law in California

Depends on the agreement with the client.

I'm not quite sure exactly what is meant by "office transaction fees," but a licensed real estate broker or salesperson and the client are pretty much at liberty to contract for compensation and expense reimbursement in any way they find fitting and proper. Although a flat commission upon the broker or salesperson fulfilling their duties to put a deal together is by far the most common arrangement, I'm sue that in practice there is a wide variety of compensation and cost reimbursement deals out there and that they are generally legal.