State is different because the funding situation of state and federal governments are not equivalent, but marginal federal spending is not tied to marginal increases in tax revenue even in principal, so quite literally changes in federal spending do not come from tax dollars.
If you assume that (1) the lifespan of the federal government is finite, and (2) the federal government will have no unpaid, transferred, forgiven, or externally covered debt from now until and including the eventual final shut-down, then it follows that any spending must eventually be covered by taxes, but while (1) is a reasonable assumption, (2) is...less clearly justified.