The National Defense Authorization Act (NDAA) is the name for each of a series of United States federal laws specifying the annual budget and expenditures of the U.S. Department of Defense. The first NDAA was passed in 1961.^[1][2] The U.S. Congress oversees the defense budget primarily through two yearly bills: the National Defense Authorization Act and defense appropriations bills. The authorization bill is the jurisdiction of the Senate Armed Services Committee and House Armed Services Committee and determines the agencies responsible for defense, establishes recommended funding levels, and sets the policies under which money will be spent.^[3] The appropriations bill provides funds.

The passage of a Defense Authorization Act is often used by Congress to honour a senior congress member or other individual. For example, the National Defense Authorization Act for Fiscal Year 2001 is known as the "Floyd D. Spence National Defense Authorization Act for Fiscal Year 2001" in honor of Representative Floyd D. Spence of South Carolina.^[4]

• Clinger–Cohen Act, part of the National Defense Authorization Act for Fiscal Year 1996
• McCarran Internal Security Act