New reporting rules requiring the filing of Form 8992, U.S. Shareholder Calculation of Global Intangible Low-Taxed Income, are also described in the proposed regulations.

The new law applies to the first tax year of a CFC beginning after Dec. 31, 2017, and the U.S. shareholder’s year with or within which that year ends, and all subsequent tax years.

The Tax Cuts and Jobs Act's tax on GILTI was a key plank in the law's international framework, which legislators said would work as a backstop to ensure companies did not take advantage of a new exemption on most foreign profits to migrate its U.S. income offshore.

GILTI includes income earned through offshore subsidiaries beyond 10 percent of their tangible depreciable assets. That income is immediately pulled in for U.S. taxation, although it receives a deduction that ultimately sets its tax rate at 10.5 percent.

The “low-taxed” part of the equation comes only after the income is identified. Because foreign tax credits apply to this income at an 80 percent rate, GILTI will result in additional U.S. tax only if it is held in a jurisdiction with a tax rate of less than 13.125 percent.