(Bloomberg) -- Business owners -- and their accountants -- can rest a bit easier: the IRS has given them the long-anticipated final word on how they can claim one of the biggest perks in the 2017 Republican tax overhaul.

The regulations detailing the new 20 percent deduction for pass-through business owners are of critical importance to the operators of such entities, who range from mom-and-pop convenience store owners to private equity investors.

The regulations, issued on Friday despite a partial government shutdown that has many Internal Revenue Service employees on furlough, can cut their tax bills by up to one-fifth, but also govern what many say is one of the most complex changes in President Donald Trump’s tax law.

The IRS made a series of changes to make it simpler for businesses to determine if they can or can’t get the tax break, a senior Treasury official said on a call with reporters.

Veterinarians, for example, don’t qualify for the deduction, but rental real estate owners that spend at least 250 hours a year involved with the business can get the deduction, according to the IRS guidance.

--With assistance from Lynnley Browning.

To contact the reporter on this story: Laura Davison in Washington at ldavison4@bloomberg.net

To contact the editors responsible for this story: Alexis Leondis at aleondis@bloomberg.net, Ros Krasny, Lynnley Browning

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