Senator Marco Rubio (R-FL) and several other congressional Republicans have proposed canceling $45 billion in unused funding that Congress provided for discretionary programs in prior years, using the savings to shrink deficits. The idea that these “unobligated balances” are a painless source of budget savings isn’t new. But it isn’t true, either, for three reasons in particular.
Even in cases where the loss of these funds wouldn’t undermine the project as a whole, it would weaken it, exactly as a similar cut in new funding would. And it is generally better to cut new money than unobligated balances if doing the latter would waste money already invested.