WASHINGTON—President Donald Trump on Wednesday is planning to unveil a proposal to cut the corporate tax rate to 15%, sharply reduce taxes on U.S. companies’ foreign profits and slash the top tax rate to 15% on so-called pass-through businesses, including many owner-operated companies, said White House officials familiar with the planning.

Mr. Trump also plans to include a tax break for child-care expenses, similar to the one he proposed during the campaign at the urging of his daughter, Ivanka, now a top White House adviser.

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