A taxpayer representative must have the skill and experience to identify and interpret the applicable tax law and also find ambiguity and inconsistency in the law to protect a taxpayer from erroneously overpaying a tax liability. The same legal skill may be used to identify the tax law that will support a legal argument in favor of a taxpayer position. Tax law is based upon legislation passed by Congress. No tax statute is comprehensive and complete. Congress cannot think of every issue that could arise under tax legislation and draft a comprehensive legislative answer for all potential technical issues.
All words have ambiguity.
Hence legislation needs to be clarified. Tax law may be interpreted within the context of the statute or related tax statutes. The language of a statute may be interpreted by language in the reports of Committee on Ways and Means of the House of Representatives, the Senate Finance Committee, or the Joint Tax Committee. Legislative intent may also be discerned from Congressional debate or colloquy. The language of a tax statute is further applied and interpreted by tax regulations drafted by the Treasury Department.