budget deficits

A black swan is a crisis that comes out of nowhere. A gray rhino, by contrast, is a problem we have known about for a long time, but can’t or won’t stop, that will at some point crash into a full-blown crisis.

The US national debt is a classic gray rhino. The problem has slowly been getting worse for 25 years, but the crisis still seems far enough off that almost no one wants to incur real costs today to solve the problem. During the 2007-2009 financial crisis and the 2020-2021 Covid pandemic we had good reasons to run deficits. But we’ve ignored the Keynesian solution of paying back the deficits incurred in bad times with surpluses in good times.

We are currently in reasonably good economic times, but about to pass a mega-spending bill that blows the deficit up from its already-too-high-levels. At a time when we should be running a surplus, we are instead running a deficit around 6% of GDP:

Our ‘primary deficit’ is lower, a more manageable 3% of GDP. But if interest rates go higher, either for structural reasons or because of a loss of confidence in the US government’s willingness to pay its debts, the total deficit could spiral higher rapidly. The CBO optimistically assumed that the interest rate on 10-year treasuries will fall below 4% in the 2030s, from 4.3% today:

But their scoring of H.R. 1 (“One Big Beautiful Bill Act”) shows it adding $3 trillion to the debt over the next 10 years, increasing the deficit by ~1% of GDP per year.

I already suspected this gray rhino would eventually cause a crisis, but this bill and the milieu that produced turn it into a near guarantee- nothing stops the deficit train until we hit a full blown crisis. That crisis is no longer just a long-term issue for your kids and grandkids to worry about- you will see it in 7 years or so. Unfortunately, that is still far enough away that current politicians have no incentive to take costly steps to avoid it. In fact, deficits will probably make the economy stronger for a year or two before they start making things worse- convenient for all the Congresspeople up for election in less than 2 years.

Here are the ways I see this playing out, from most to least likely:

By around 2032, either the slowly aging population or a sudden spike in interest rates forces the government to touch at least one of the third rails of American politics: cut Social Security, cut Medicare, or substantially raise taxes on the middle class (explicitly or through inflation).
We get bailed out again by God’s Special Providence for fools, drunks, and the United States of America. AI brings productivity miracles bigger than those of computers and the internet, letting GDP grow faster than our debts.
We default on the national debt (but this is a risky option because we will still want to run big deficits, and lenders will only lend if they expect to get paid back).
We do all the smart policy reforms that economists recommend in time to head off the crisis and stop the rhino. Medical spending falls without important services being cut thanks to supply-side reforms or cheap miracle drugs (GLP-1s going off patent?).

I’m hoping of course for numbers 2 and 4, but after this bill I’m expecting the rhino.

The Tax Cuts and Jobs Act was passed in late 2017 and went into effect in 2018. For academic research to analyze the effects, that’s still a very recent change, which can make analyzing the effects challenging. In this case the challenge is especially important because major portions of the Act will expire at the end of next year, and there will be a major political debate about renewing portions of it in 2025.

Despite these challenges, a recent Journal of Economic Perspectives article does an excellent job of summarizing what we know about the effects so far. In “Sweeping Changes and an Uncertain Legacy: The Tax Cuts and Jobs Act of 2017,” the authors Gale, Hoopes, and Pomerleau first point out some of the obvious effects:

TCJA increased budget deficits (i.e., it did not “pay for itself”)
Most Americans got a tax cut (around 80%), which explains #1 — and only about 5% of Americans saw a tax increase (~15% weren’t affected either way)
Following from #2, every quintile of income saw their after-tax income increase, though the benefits were heavily skewed towards the top of the distribution ($1,600 average increase, but $7,600 for the top quintile, and almost $200,000 for the top 0.1%)

Beyond these headline effects, it seems that most of the other effects were modest or difficult to estimate — especially given the economic disruptions of 2020 related to the pandemic.

For example, what about business investment? Through both lowering tax rates for corporations and changing some rules about deductions of expenses, we might have expected a boom in business investment (it was also stated goal of some proponents of the law). Many studies have tried to examine the potential impact, and the authors group these studies into three buckets: macro-simulations, comparisons of aggregate data, and using micro-data across industries (to better get at causation).

In general, the authors of this paper don’t find much convincing evidence that there was a boom in business investment. The investment share of GDP didn’t grow much compared to before the law, and other countries saw more growth in investment as a share of GDP. Could that be because GDP is larger, even though the share of investment hasn’t grown? Probably not, as GDP in the US is perhaps 1 percent larger than without the law — that’s not nothing, but it’s not a huge boom (and that’s not 1 percent per year higher growth, it’s just 1 percent).

Ultimately though, it is hard to say what the correct counterfactual would be for business investment, even with synthetic control analyses (the authors discuss a few synthetic control studies on pages 21-22, but they aren’t convinced).

What’s important about some of the main effects is that these were largely predictable, at least by economists. The authors point to a 2017 Clark Center poll of leading economists. Almost no economists thought GDP would be “substantially higher” from the tax changes, and economists were extremely certain that it would increase the level of federal debt (no one disagreed and only a few were uncertain).