While writing the tax reform bill, Republicans in Congress had to balance tax cuts that would expand the federal deficit with measures to ensure that the increase in the deficit would not be larger than congressional rules allow. One of the ways they did this was by setting an end date for individual tax breaks in order to offset the new 21 percent corporate tax rate. A less reported way is through a “global intangible low-taxed income” levy, or GILTI, which Bloomberg describes as “little-understood.”

GILTI is meant to prevent U.S. companies from shifting profits to other countries with lower tax rates, like Ireland, reports Bloomberg. For corporations, it would only apply when a company’s overseas tax bill is below a set threshold, but according to Bloomberg, partnerships and other pass-through businesses would face much higher tax rates on foreign income. Miami Tax partner Michael Kosnitzky agrees.

“Partnerships get slammed,” he told Bloomberg. “They’re not being treated as well as C corporations.”

Read more about GILTI on Bloomberg.