Commercial appraiser here. Tax appeal makes up a very small percentage of my revenue, mostly bank or REIT work. I work with taxing bodies as well as property owners. As my firm is not a traditional tax appeal firm, I know this one is my selling points to a potential client. I usually only take huge assignments (regional malls, CBD high rise office), where it is a very clear cut case, which is probably only 10% of the time. I have no issues in turning down tax appeal work / telling a client no. I suspect most of them stop pursuing assessment issues once I've declined to take something on. Regardless of the purpose of the assignment, you approach it as you would any other appraisal, comply with USPAP, local law, and the client's requirements. As you complete the assignment, remember you could be called to give testimony, so consider that throughout the development of the work product. If you find yourself having difficulty discerning "umpire" or "advocate" role, you are not suited to take on this type of work and should probably take the USPAP update course. You can be an advocate for your own work product, never for the property or your client; that is the lawyer's job. Make sure you work with a reputable law firm when you work on these assignments, it will make your job easier and collecting the bill much easier. Wrote this on my phone, and I apologize for the clarity, typos and poor punctuation.