The purpose of this guide is to serve as a Federal Tax Law research tool. This guide covers the major tools and sources of tax law in the United States, including primary sources, secondary sources, major research databases in this area, and other useful tools for researching federal tax law, such as research guides and tool kits. While the resources listed in this guide are not designed to be exhaustive, it provides a starting point that identifies the major resources and authority necessary for tax law research.
The following chart is a hierarchical representation of the authority of tax laws, regulations, court opinions and publications at the Federal level. This guide covers research relating to each of the sources of authority listed below. The chart lists legal authority top to bottom, from most important to least.
Although this guide primarily covers resources and materials related to Federal Income Tax, many of the resources listed within are applicable to other areas of tax law research.

Source: Treas. Reg. §1.6662-4(d)(3)(iii).

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