Misses like this tell you that forecasters are missing a change in the structure of the economy. Two candidates for why this is happening are a significant increase in global liquidity and what the economist Larry Summers has dubbed “secular stagnation.”

Globalization and the spread of so-called financialization — the growth of interconnected financial markets in economies across the globe — have led to a significant increase in the sheer amount of capital and thus the stock of loanable funds. That increased supply has lowered the cost of capital in ways the models are missing.

The stagnation point is more sobering. Bond rates are also pushed down by future expectations about growth and inflation. Especially in the case of longer-term yields like the 10-year bond, investors want to be paid more (that is, they want a higher yield) because of the opportunity cost of locking up their cash over a period when they think growth will be strong. Falling yields could thus signal lowered growth expectations.

This pattern is important because of what it says about future debt payments and pressures to cut the federal budget. Both recent forecasts on Treasury rates from the Congressional Budget Office and the Blue Chip (the consensus among private sector economists) are about the same as the administration’s.

The forecasts implied by so-called “forward rates” — rates bond traders can lock in today — for the 10-year bond have adapted more rapidly to the systemic errors and have it sitting about where it is now, around 2 percent, for the next decade. If that’s right, it means, all else being equal, the debt-to-G.D.P. ratio will be six percentage points lower in 2025 than the administration is forecasting, a large and significant difference in coming fiscal pressures.

But this observation comes with numerous caveats, the first of which is most salient. Who knows where interest rates will be in 10 years? Even if the market forecasters are correct, our future debt burden is ameliorated, not erased, and so there are still good reasons to tread cautiously. From my own perspective, the point of these figures is not that we’re on a long-term, sustainable budget path. It’s simply to suggest that based on our recent track record, we may well be overestimating the cost of future debt service and demanding more budget restraint than is necessary.

Second, note the “all else being equal” clause above. If interest rates are coming in lower than predicted because growth is also coming in lower, low growth will cancel out some of the fiscal benefits of low rates. Forecasters have been less systematically wrong regarding G.D.P. growth, and they’ve broadly marked down future growth rates already. That’s led some economists, including Paul Krugman, to question why the lower growth forecasts don’t seem to square with the expectation that rates will bounce back up.