WASHINGTON — The Treasury Department said on Thursday that it was rolling back regulations issued under the Obama administration that were enacted to prevent American companies from moving their official residence abroad to reduce their tax bills.

The regulations are no longer necessary, Trump administration officials say, because of changes made in the tax overhaul that President Trump signed in 2017. The changes reduced taxes on American companies and included provisions meant to discourage these so-called inversions. In an inversion, an American company merges with a foreign firm and becomes its subsidiary, effectively moving its headquarters abroad for tax purposes.

The previous regulations, issued over the course of President Barack Obama’s second term, were credited by many tax analysts with reducing inversions. Business groups criticized the regulations, and the United States Chamber of Commerce sued to block one set of the rules, calling them “unauthorized and unlawful.”

In a news release, the Treasury secretary, Steven T. Mnuchin, referred to the 2017 law, the Tax Cuts and Jobs Act, saying that it “leveled the playing field for American businesses.”