The primary sources of tax law are the Internal Revenue Code (IRC), associated regulations, and case law. The IRC is the body of law that lays out the rules for federal taxes. These rules are enacted by Congress and signed by the president.
The Treasury Department then issues regulations to provide further guidance on how the tax laws should be interpreted and applied. Regulations are typically promulgated under a notice and comment process, which allows the public to weigh in on proposed regulations before they become final. After a regulation is finalized, it has the force of law.
In addition to these primary sources, taxpayers may also look to Secondary Sources for guidance on their tax obligations. Examples of secondary sources include Internal Revenue Service (IRS)