United States Government Accountability Office September 2016 Report to Congressional Requesters found that The Internal Revenue Service (IRS) uses a variety of documents to communicate its interpretation of tax laws to the public, but only considers Internal Revenue Bulletin (IRB) guidance to be authoritative. IRS information published outside of the IRB can help taxpayers understand tax laws and make informed decisions, but does not always include information clarifying the limitations of its use. IRS has detailed procedures for identifying, prioritizing, and issuing new guidance. However, it lacks procedures for documenting the decision about what type of guidance to issue.

It concluded that Treasury and IRS produce large numbers of regulations and guidance documents for the public every year. IRS uses a variety of documents to communicate its interpretation of tax laws to the public, but only considers guidance published in the IRB to be authoritative. However, IRS does not always clearly identify the extent to which certain documents published outside the IRB can be considered authoritative for use by the public. While IRS does have detailed procedures for identifying, prioritizing, and issuing new guidance, it lacks documented procedures for deciding what type of guidance to issue. Policies and procedures that identify factors to consider when deciding among different guidance types could help IRS ensure that the selected form of guidance reflects what is known about the binding nature of various types of guidance.

The report can be read here: http://gao.gov/assets/680/679518.pdf