June 17, 1985

The assertion last week by Treasury Secretary James A. Baker 3d that ''the median-income family'' in every state would be better off under the Reagan Administration's tax plan is not borne out by an analysis of Government statistics. The figures show that in New York and several other states, couples with two wage-earners, two children, typical deductions and the median income for a family of that size in their state would owe slightly higher taxes under the Reagan proposals than they would owe if the law is not changed. Mr. Baker's assertion, in testimony before the Senate Finance Committee, was based on the premise that a family with median income - the level at which half the families earn more and half earn less - had only one wage-earner. Study of 2-Paycheck Homes Internal Revenue Service statistics show, however, that two-thirds of the couples earning between $30,000 and $40,000, the range where the median income falls in most states, have two wage-earners. Those families, under the present law, are entitled to a tax deduction that the President proposes to abolish.

President Reagan in a speech in New Jersey last week reasserted his belief that his tax plan would not hurt taxpayers in ''high-tax'' states such as New York. But neither the President nor his lieutenants have ever denied that many New Yorkers would face a big tax increase. And while Governor Cuomo has insistently denounced as unfair a key Reagan provision, the proposal to end the deduction for state and local taxes, the Governor has not contested that a great many New Yorkers - not all of them rich - would enjoy substantial tax cuts. The dispute heated up this weekend, when Patrick J. Buchanan, the White House director of communications, described Mr. Cuomo as a ''glib, fast-talking lobbyist for a reactionary liberalism that would kill tax reform in its crib.'' The charge was made in a letter to The New York Times.

President Reagan today warned Moslem Shiite hijackers ''for their own safety'' to free the American hostages on a Trans World Airlines jet in Beirut as well as the passengers removed Friday night to an undisclosed location. Mr. Reagan, who met this afternoon with advisers, also affirmed the United States policy of refusing to negotiate with terrorists. ''This has always been a position of ours,'' said Mr. Reagan, who returned early from a weekend at Camp David, Md., to confer with aides. At Least 40 Hostages The hijackers have killed one passenger and are holding at least 40 Americans hostage in Lebanon.

A political bargain that limits deployment of the MX missile, as well as problems with the planned Midgetman missile, have cast new doubt on the future of land-based missiles in the country's nuclear arsenal, according to Pentagon officials and members of Congress. The officials and some lawmakers say they are worried that the United States in the next decade will become dangerously dependent on missile-carrying submarines and bombers to retaliate in the event of a nuclear attack. The Reagan White House, like the previous Administration, has expressed steady concern that existing land-based missiles are vulnerable to a Soviet surprise attack and that the missiles are aging while the Soviet Union is improving its force. Problems Facing Midgetman The MX, a huge 10-warhead intercontinental missile favored by the Administration, has encountered relentless political opposition, and most Administration officials have abandoned hope that it will become the mainstay of the missile force. In addition, many strategic planners said, little notice has been given to formidable problems facing the Midgetman, a smaller, single-warhead mobile missile that is favored by many Democrats as a long-term solution.

Andy North had not won a tournament since taking the 1978 United States Open and did not seem destined to win today in the final round of the 85th Open - not unless something happened to Tze-Chung Chen, who led by four shots with 14 holes to go at Oakland Hills Country Club. Then, in one of those inexplicable twists, Chen took a quadruple bogey 8 at the par-4 fifth hole to open the door for North and three others still in the running. Chen struck his ball twice on one stroke, suffering a one-shot penalty as he got that 8. North was the only one able to take full advantage. Despite one of the poorest final rounds by an Open champion in the last half century, North's four-over-par 74 was just good enough for to finish at one-under-par 279 and beat Chen, Denis Watson of South Africa and Dave Barr of Canada by one shot.