Looseleaf services combine both primary and secondary sources on tax law into a useful research tool. In general, each looseleaf service prints the text of Tax Code sections alongside the related Treasury regulations, and then provides an annotated list of cases, administrative rulings, and other documents related to that Code section. Each Code section is also accompanied by explanatory secondary material. Because of this arrangement, they are particularly suited for researching issues dealing with specific sections of the Tax Code. For issues involving the relationships between multiple sections of Code, secondary sources that are subject-based (such as treatises, handbooks, or encyclopedias) may be better.
Looseleaf services are organized in Code section number, but also contain subject matter indexes, as well as other finding aids. Looseleafs are updated frequently, often weekly or bi-weekly, and can be available in print or electronic formats.