There is an idea that had merit: the government should never spend more than it takes in. That is how a government ought to function. The problem we are running into now is that interest on the national debt is growing faster than revenue and claiming a larger share of every tax dollar. Under the CBO's latest long-term outlook, net interest is projected to reach about 37% of revenues by 2056. Put another way, in 2000, net interest was about 11% of federal revenue