The Democrats lied. Read this:
Under their “Pay-Go” rules, congressional Democrats promised not to raise spending unless there was specific federal revenue available to pay for it. The Reserve Fund is their way of guaranteeing a funding increase when — wink, wink — at a later date they will have found the needed revenues. Call it the “Spend Now, Maybe Pay Later” approach to federal budgeting.
Pay-as-you-go was originally a Republican idea, embraced by them in their years out of power when they were outraged at Democratic profligacy. Their outrage dissipated when they seized power.
Still, it was a promise made by Democrats, and it was a promise broken. Remember it when politicians wail about the deficit. Spending, not a lack of revenue, is the real problem.