Constitutional Amendment - Requires the concurrence of two-thirds of the Members of each house of Congress for final adoption of any legislation changing the internal revenue laws, unless such legislation is determined not to increase the internal revenue by more than a de minimis amount.

Permits a waiver of this requirement when a declaration of war is in effect or when the United States is engaged in military conflict which causes an imminent and serious threat to national security and is so declared by a joint resolution which becomes law. Prohibits any increase in the internal revenue enacted under such a waiver from lasting more than two years.