The Internal Revenue Services publishes a vast array of material for itself, practitioners, and taxpayers. Most of the information is public and published on its website, including Revenue Rulings and Procedures, the Internal Revenue Manual, and its database of Forms, Instructions, and Publications . Some of the information, like Determination Letters and Technical Advice Memorandums are designed for issues concerning individual taxpayers, but made available through the Freedom of Information Act (FOIA).
Revenue Rulings and Procedure are published weekly by the Commissioner of Internal Revenue in the Internal Revenue Bulletin. The Internal Revenue Bulletin can be found online on the IRS's website, but, the search function does not seem to support a keyword search. Revenue Rulings are helpful for a variety of tax procedure issues, and they are often referenced in the practice centers and secondary sources.
Revenue Rulings are official administrative rulings that explain how the IRS applies a statute or regulation to a set of given facts. These rulings will also explain how the IRS applies the holding of case law, whether it acquiesces and gives the decision its full effect, or why it believes the holding is limited to the specific facts of the case.
Revenue Procedures are official statements which provide how a statute, regulation, or ruling should be applied to a tax return or other document submitted to the IRS. Many Revenue Procedures guide practitioners and taxpayers in collection issues, such as Innocent Spouse Petitions and Offers in Compromise.
While they don't have the same weight as statutes, regulations, and case law, Revenue Rulings and Procedures can still serve as persuasive precedent.
Additional Sources
In addition to what is available through the IRS website, the IRS Revenue Rulings and Procedures are also available in commercial databases like Westlaw, and Bloomberg Law. The links will take you to search functions which have limited the scope of the search to the IRS Revenue Rulings and Procedures.
Finding Revenue Rulings and Procedures in Lexis+ is also possible, but for whatever reason, they are not directly available through their tax practice area page. You can instead search for them using the Lexis' Tax page or use this link.
If you need a free resource, you can search for Revenue Rulings and Procedures through Tax Note's "IRS Guidance" page.
The Internal Revenue Manual (IRM) is basically the IRS employee handbook. It contains instructions on how to carry out administrative and procedural matters. Although the IRM is not the law and it is not binding on the IRS, it still has value to practitioners in that it shows how the IRS audits different areas of a tax return and the information that the IRS can request from the taxpayer. The IRM also contains information and areas of relief that are not available anywhere else. For instance, it contains information on “first-time abate” procedures which allow the IRS to remove penalties associated with a taxpayer’s failure to file tax returns or pay their taxes when certain circumstances are met. You can find it on the IRS's website in the link above or browse and search for versions maintained by the commercial databases:
For help with understanding the IRM, you can to Brian E. Gates, Internal Revenue Manual (IRM) Abridged & Annotated, (rev. ed.), Westlaw (database updated June 2022). This resource explains the purpose of the different parts of the IRM and explains how the parts are used.
The IRS publishes annual forms and instructions which are designed to help a taxpayer file their taxes. IRS Publications and Tax Forms can be found on the www.irs.gov website by clicking on the “Find Forms & Instructions” link.
While they do not have the weight of law, these publications show what the IRS believes to be the “best practices” for taxpayers. It includes forms such as Form 1040, and links to .pdf files containing instructions for filling out the forms. You can also navigate these in order by clicking on the “List All Current Forms & Instructions” link or search for publications in the website’s search bar.
If you are having trouble locating a specific form, instruction, or publication, you can also use search engines such as www.google.com by typing “IRS publication (your topic).” For instance, typing “IRS publication travel expenses” into a Google search yields top results for links to “Publication 463: Travel, Gift and Car Expenses” along with Topic No. 511 Business Travel Expenses on the IRS website.
If you are so inclined, you can also use the links below to search for forms using the commercial databases:
Private letter rulings and determination letters are created when the IRS responds to questions asked by individual taxpayers. While they are private in nature and cannot be relied upon as legal authority in themselves, they can provide helpful insight and guidance on very specific tax issues.
Written determinations are made openly available at www.irs.gov/written-determinations and updated weekly. You can also do keyword searches for them using the following commercial sources:
Technical advice memorandums (TAM) are similar to letter rulings, but they are obtained during an IRS proceeding, made by the IRS Office of Chief Counsel for the IRS Appeals Area Director. If you're looking for TAMS, specifically, you can use the free database provided by Tax Notes.