The other responses have the right idea, but in more detail:

All congressional bills receive an estimate of their budget impact over the next ten years. Whatever happens after ten years doesn't count.

The politics are that a bill should have no budget impact within that ten-year window. As an uncharitable stylized example, you'd propose to start paying random subsidies to constituents immediately in the amount of $200M / year, forever. 8 years out, you also plan to raise taxes on somebody else, someone who would never vote for you in a million years, in the amount of $1B / year, which may or may not fade out after two years. This is a bill with no budget impact.

It doesn't matter, to you, whether that spike in collections for years 9-10 actually happens or not. If you failed at targeting it exclusively to people you hate, you might prefer that it doesn't.