But beyond the obvious problems, the proposed change in the tax code would cascade through the economy in many other ways.

A 25 percent rise in the value of the dollar, the most widely used currency on the planet, would have enormous consequences. Supporters think the dollar will rise that much if the plan is enacted — indeed, it must happen, to avoid sticking Americans with much higher prices for imported consumer goods.

But according to calculations by Michael J. Graetz, a Columbia law professor, a currency shift of that scale implies that Americans who hold foreign assets would lose $6.1 trillion, and foreign holders of assets in the United States would gain as much as $8.1 trillion. Meanwhile, because the dollar is the world’s benchmark currency, many businesses and governments outside the United States borrow in it, especially in emerging-market countries where confidence in the domestic currency is low.

That means that a steep run-up in the value of the dollar generally makes those debts more onerous, and causes big trouble for countries including China, South Korea and Turkey. Consider that the Asian financial crisis in 1998, the Latin American crisis in 2001 and an emerging markets slump in 2015 all had their roots in debt problems and a spike in the dollar.

What’s more, global markets in oil and other commodities are priced in dollars, so a dollar spike could unleash hard-to-predict reactions from commodity producers. Oil would become much more expensive, and oil price shocks have helped set off recessions in the not-too-distant past.

Perhaps the most irony-rich consequence of such a tax overhaul — which would, presumably, be signed by President Trump — would be the damage to the tourism and education sectors in the United States. These businesses would have a serious problem, unlike conventional exporters — companies that ship things overseas, say.

For the exporters, the disadvantages caused by a run-up in the dollar would just cancel out the advantage received from changes in the tax system. But businesses that are not exporting anything across the border would suffer from the damage of a more expensive dollar without receiving advantages from border adjustment.