But at the same time, mainstream macroeconomic models have the economic lift from tax cuts fading sometime between 2020 and 2022. That means the Fed could be raising interest rates to slow the economy just as tax policy is also working to slow the economy.

Both affect the economy with unpredictable lags, so it could prove hard for the Fed to set policies that can prevent both overheating in 2019 and 2020 and a downturn in 2021 and 2022.

“There is probably some kind of perfect path where the Fed could thread the needle on this,” raising rates just enough to prevent overheating but not enough to leave rates so high as to risk a recession once the impact of tax cuts fades, Mr. Guha said. “But what’s the likelihood that you’ll thread that needle? It’s not one you’d want to be betting the farm on.”

The former Federal Reserve chairman Ben Bernanke put it more colorfully at a conference in June. The stimulative benefit of the tax cut “is going to hit the economy in a big way this year and the next year,” he said. “And then in 2020, Wile E. Coyote is going to go off the cliff.”

Pop Goes the Debt Bubble

The last two recessions started with the popping of an asset bubble. In 2001 it was dot-com stocks; in 2007 it was houses and the mortgage securities backed by them.

So it makes sense to look to various markets that might be getting bubbly in dangerous ways. And that search leads quickly to debt markets, both in the United States and overseas.

Corporations have loaded up on debt over the last decade, spurred by low interest rates and the opportunity to increase returns for shareholders. The value of corporate bonds outstanding rose by $2.6 trillion in the United States between 2007 and 2017, according to data from the McKinsey Global Institute — rising to about 25 percent of G.D.P. from about 16 percent.