IRS’s mission is to provide America’s taxpayers top quality service by helping them understand and meet their tax responsibilities and enforce the law with integrity and fairness to all. For more than 100 years, Treasury, in conjunction with IRS, has issued tax regulations and other guidance documents to help taxpayers comply with the tax code. Treasury and IRS are among the largest generators of federal agency regulations and they issue thousands of other forms of taxpayer guidance. The Internal Revenue Code (IRC) authorizes the Secretary of the Treasury to “prescribe all needful rules and regulations for the enforcement of” the code. IRS publishes tax regulations and other guidance in the weekly IRB. Each annual volume of the IRB contains about 2,000 pages of regulations and other guidance documents. In addition to the guidance published in the IRB, thousands of other documents that provide information to taxpayers are available on IRS’s website. Some IRS guidance written by the IRS Office of Chief Counsel provides detailed and technical explanations of tax laws for professional return preparers as well as taxpayers. Other IRS sources of information that explain tax law in “plain language” include: forms, instructions, and publications for taxpayers to use in preparing their returns; news releases, fact sheets, and tax tips to the news media; online interactive tools in which taxpayers can receive answers after asking general or taxpayer-specific questions; and instructional audio and video presentations. These various communication tools are intended to help taxpayers understand tax laws, improve voluntary compliance, and control IRS’s administrative costs. IRS’s policies and procedures for producing regulations and other guidance cite five legal authorities for IRS to follow when drafting and issuing regulations: the Administrative Procedure Act (APA), the Paperwork Reduction Act (PRA), the Regulatory Flexibility Act (RFA), the Congressional Review Act (CRA), and a section of the IRC. APA generally requires that agencies notify the public about, and solicit comments on, proposed regulations via a notice of proposed rulemaking (NPRM) in the Federal Register. PRA requires agencies to minimize the paperwork burden they impose on the public, and submit certain proposed information collections to OMB for approval. RFA generally requires agencies to consider the impact of their regulatory proposals on small businesses and other small entities, analyze effective alternatives that minimize small entity impacts, and make their analyses available for public comment. CRA requires agencies to submit each rule to Congress and to the Comptroller General before it can take effect. All agencies are also required to specify whether the rule is “major” under CRA; but OIRA is responsible for determining whether a rule is major based on certain criteria. We issue reports to Congress on major rules, summarizing and assessing the agency’s compliance with required procedural steps. Presidents have issued executive orders to centralize review of executive branch agency rulemaking within OMB, and to require executive branch agencies to prepare additional assessments and analyses of the potential costs and benefits of significant and economically significant rules. OIRA is the OMB organization responsible for the coordinated review of regulatory actions by executive agencies. Such coordinated review is necessary to ensure that, among other things, regulations are consistent with applicable laws, the President’s priorities, and the principles set forth in executive orders, and that decisions made by one agency do not conflict with the policies or actions taken or planned by another agency. Executive agencies provide OIRA with lists of planned regulatory actions when drafting rules, including assessments about whether the rules are significant under Executive Order (E.O.) 12866, to determine if additional OIRA review is required. If so, agencies provide the text of the draft regulation and any required analyses (including information on estimated costs and benefits) to OIRA before issuing the rule. OIRA staff review the rule and related documents and may request changes or additional analyses. OIRA can notify the agency that it has separately determined that a planned regulation is a significant regulatory action. OIRA also has a responsibility under CRA for determining when rules issued by executive branch and independent regulatory agencies are major. OIRA is responsible for reviewing certain non-regulatory guidance issued by executive branch agencies. OMB issued a bulletin in 2007 to establish policies and procedures for the development, issuance, and use of “significant” guidance documents by executive branch agencies. The bulletin’s definition of a significant guidance document is similar to the definition of a significant regulatory action under E.O. 12866. The bulletin requires that agencies establish procedures to allow the public to view and comment on significant guidance documents after they are released and, for any economically significant guidance documents, also make a draft available for public comment and announce its availability in the Federal Register. Consistent with an OMB memorandum implementing the bulletin, OIRA has the opportunity to review some significant guidance documents prior to issuance. Guidance that is not significant (as defined by the OMB bulletin) is not subject to policies and procedures in the bulletin, and guidance procedures are left to agency discretion. Although IRS issues thousands of publications in a variety of different forms to help taxpayers and their advisors understand the law, IRS has stated that only guidance published in the IRB contains the IRS’s authoritative interpretation of the law (see figure 1). Internal Revenue Code (IRC). Federal tax law begins with tax provisions enacted by Congress and codified in title 26 of the U.S. Code as the IRC. Consequently, the IRC is the most authoritative source of information for taxpayers. It is the codified collection of U.S. laws on income, estate and gift, employment, and excise taxes, plus administrative and procedural provisions. Treasury (tax) regulations provide Treasury’s and IRS’s official interpretation of tax laws. Regulations are the most authoritative source of published guidance, and they are binding on taxpayers and IRS since they have the force and effect of law. They are published both in the IRB and the Federal Register. Other IRB guidance (revenue rulings, revenue procedures, notices, and announcements) do not have the same “force and effect” of Treasury regulations, but taxpayers can still rely on them as authoritative. For example, taxpayers can use IRB guidance to support a position knowing that IRS is bound by IRB guidance because IRS employees must follow it. Written determinations are Chief Counsel letters to, or memorandums regarding, individual taxpayers; but IRS cautions that only the taxpayer addressed by the guidance can rely on it as precedent. Every year, the Chief Counsel issues thousands of private letter rulings to taxpayers or their advisors who request (for a fee) answers to technical questions about potential tax consequences of particular transactions. The Chief Counsel also issues technical advice memorandums to IRS offices that have technical or procedural questions about an individual taxpayer case. When written determinations are later published via the IRS website, they often contain disclaimers noting any legal limitations. Other IRS publications and information are described in the Internal Revenue Manual (IRM) as “a good source of general information.” However, the IRM states that these documents cannot be relied upon by taxpayers as authoritative or as precedent for their individual facts and circumstances since they are not binding on IRS. Tax practitioners and other tax law experts note that courts have ruled that taxpayers cannot rely on IRS documents published outside the IRB to support a position. The form that information in this category can take varies widely, and includes IRS videos, online tools, forms and publications, and Frequently Asked Questions (FAQs). Guidance published in the IRB goes through a multi-step clearance process at both Treasury and IRS, involving review and approval by officials in a wide variety of Treasury and IRS offices. The weekly IRB is described as the “authoritative instrument” for publishing official IRS rulings and procedures and tax regulations. This distinction is important because, according to IRS officials, only guidance published in the IRB is binding on IRS and can be relied upon by taxpayers as authoritative. The five types of guidance published in the IRB are: regulations, revenue rulings, revenue procedures, notices, and announcements. Tax regulations are also published in the Federal Register and codified in the Code of Federal Regulations like other federal agency regulations. Table 1 describes the types of IRS guidance published in the IRB. From 2013 to 2015, the IRB (52 weekly issues) contained nearly 300 guidance documents per year, as shown in figure 2, that total about 2,000 pages. From 2002 to 2008, the number of IRB items published annually was higher (about 500 items), but starting in 2009 that number began to decline. IRS officials told us that, from 2002 to 2003, the then-Chief Counsel diverted resources away from litigation and toward the issuance of guidance, in particular revenue rulings, which contributed to the increasing counts of guidance documents during these years. Regarding the recent decline in the number of guidance documents issued, IRS officials said that hiring freezes have reduced the total number of chief counsel attorneys by 14 percent from 2011 to 2015. They also said that issuance of complicated regulations to implement the Patient Protection and Affordable Care Act (PPACA) and the Foreign Account Tax Compliance Act (FATCA) has contributed to fewer overall guidance documents being issued in recent years. Even though IRS officials told us that only documents published in the IRB constitute guidance, and can be relied upon by taxpayers as authoritative and as precedent for their individual circumstances, limitations on the use of other IRS documents is not always clearly communicated to taxpayers. IRS officials said that the agency distinguishes between official guidance published in the IRB and its thousands of other documents by explaining that information in the IRB can be relied upon as authoritative and that it is binding on IRS. Some taxpayers with relatively uncomplicated tax questions may only need to consult instructions or publications written in plain language for the general public. Other taxpayers with complicated returns or transactions may require more technical, but also more authoritative, guidance.