Field Service Advice Basics. Field Service Advice (FSA) is case specific advice provided to examiners by the Associate Chief Counsel. FSA does not represent a final determination of the Service's position, even in the case for which it was requested. (Requests for Field Service Advice, I.R.M. § 4.8.8.12.1.3) The IRS has phased out FSAs. Below is a pertinent abbreviation. Federal Service Advice Memorandum=FSA or F.S.A.