One of the difficulties in dealing with the federal tax code, in addition to its sheer size and complexity, is attempting to understand the ecosystem of administrative law that exists within the Internal Revenue Service (IRS).
The Internal Revenue Code (IRC) is enacted by Congress and is largely the product of the Joint Committee on Taxation (JCS). This body of law is merely the starting point for many elements of tax law. Supporting that are the Treasury Regulations, which appear in the Code of Federal Regulations (CFR), which number in excess of 10,000 pages.
Additional administrative tax materials include such diverse items as Chief Counsel Advice, Cumulative Bulletin, Field Service Advice, Private Letter Rulings, Revenue Procedures, Revenue Rulings, and Technical Advice Memoranda among almost 40 publications.
There is also the Internal Revenue Manual, which is essentially the guidebook for IRS employees. Disputes within the administrative world can then be taken to a court, and the choice of a court is not straightforward. Cases can be filed with the U.S. Tax Court, the Court of Federal Claims or a U.S. District Court.
Tax Court may be the first choice, as a requirement to file in the other types of court require that you pay the tax first, then litigate for the return of the disputed obligation.
The internal structure of the IRS and how all of the parts work, sometimes together, and sometimes not, are important when deciding how to respond to issues involving your taxes.
This is why most individuals or businesses find they need to hire experienced tax counsel for both matter of tax planning and tax litigation, as with the tax code, you have to know the parts to understand the whole, and you need to understand the whole to understand the parts.