Kathy Bushkin, who has been a vice president for corporate affairs for U.S. News & World Report, has been named executive editor of the magazine. Bushkin, who was a press secretary to Sen. Gary Hart for nearly nine years, which included his attempt to capture the presidential nomination last year, will take over her new position in charge of news department administration on July 1. She replaces Ben F. Phlegar, who is retiring . . .

With tax reform big on the president's agenda this year, the current Money magazine reports that President and Mrs. Reagan's tax bill would drop about $28,000 if key aspects of the tax reform proposal are enacted and their finances remain roughly the same as they were in 1984. When asked about it yesterday, the president said, "I think that just points out for everyone how advantageous the new tax system is." The Reagans' net worth is placed at about $4.4 million, up about $750,000 to $1 million from their worth when Reagan took office in 1981 . . .

Richard Carpenter, whose sister Karen died two years ago, is going to record his first solo album next month. Aware how hard it will be for him to stand on his own after all the years of success with his sister, he said: "People will listen to some songs and say, 'Oh, that's great, but it would have really been great if Karen were singing lead.' And I will understand that completely because I'll be among them." . . .