Step 2: Locate the Authority
Establishing the specific facts for your particular tax question can help narrow down the search for the appropriate authority. "Authority" comes from many sources including Congress, the Courts, and the Internal Revenue Service. In general, a tax authority can be classified as either a "primary" or "secondary" authority. Primary authority comes from statutory, administrative, and judicial sources. Secondary authority consists of unofficial sources of tax information such as tax services, journals, textbooks, and newsletters.
In many cases it may be easier to start your search with one of the secondary sources, such as one of the tax services, which will then refer you to the appropriate Internal Revenue Code section, Treasury Regulation, or pertinent court case. The following table shows the different types of "primary" and "secondary" authority with links to more detailed information on where to find these sources, how to interpret and use them, and their hierarchy of authority.
| Primary Sources | Secondary Sources |
| Legislative Sources | Tax Services |
| U.S. Constitution | Annotated Services |
| Tax Treaties | Topical Services |
| Internal Revenue Code | IRS Publications |
| Administrative Sources | RS Press Releases |
| Treasury Regulations | Tax Journals and Newsletters |
| Revenue Rulings | |
| Revenue Procedures | |
| Letter Rulings | |
| Other Pronouncements | |
| Judicial Sources | |
| Tax Court | |
| Tax Court, Small Cases Division | |
| District Courts | |
| Claims Courts | |
| Circuit Court of Appeals | |
| Supreme Court |
Once you have located the appropriate authority you need to assess the importance of that authority, its application to your particular situation, and if there are any overriding circumstances that need to be accounted for.