WASHINGTON (Reuters) - The U.S. Treasury on Friday released final regulations for a tax deduction of up to 20 percent for U.S. businesses organized as so-called pass-through entities, under President Donald Trump’s 2017 overhaul of the U.S. tax system.

FILE PHOTO: A sign marks the U.S Treasury Department in Washington, U.S., August 6, 2018. REUTERS/Brian Snyder

The 247-page document lays out how to determine the amount of deduction available to the owners of businesses that operate as sole proprietorships, partnerships, S-corporations, trusts and estates.

Treasury also proposed new regulations for the real estate industry, including a safe harbor rule to ensure access to the deduction for companies involved in the rental real estate market. Proposed rules also allow mutual fund shareholders to receive deductions on dividends from real estate investment trusts.

About 30 million U.S. businesses, including many small “Mom and Pop” firms, are organized as pass-through entities. Rather than operating like corporations with shareholders, as many large companies do, these businesses pass profits through to their owners as personal income.

The regulations, delayed slightly by the partial U.S. government shutdown, were released 10 days ahead of the Jan. 28 start of the filing season for 2018 income taxes, senior Treasury officials said.

The 2017 law gives pass-through owners only temporary tax relief that is due to expire after 2025. Until then, the regulations ensure that business owners receive the full 20 percent deduction on business income up to $315,000 for married couples and $157,500 for single filers.

For incomes above those levels, the deduction is limited by a sum equal to half of the taxable employee wages paid by the business, or a combination of 25 percent of wages plus 2.5 percent of the value of tangible property, whichever is greater.

Higher-income business owners who qualify can enhance their deductions under the final regulations, which allow both owners and pass-through entities themselves to combine ownership stakes in multiple firms including real estate businesses to minimize deduction limits, officials said.

Specified industries including healthcare, law, accounting and consulting do not qualify. But the real estate industry, where Trump and his family have business holdings, receive the benefit, as do architects and engineers.

But the final regulation allows businesses with small amounts of income from those areas to claim the deduction, officials said.