September 26, 1986

With a majority of both parties in support, the House of Representatives gave its final approval today to legislation creating a new Federal income tax system. The landmark measure now goes to the Senate, where a final vote adopting the bill is expected in the next few days, and then to the White House for President Reagan's signature. The President made enactment of the tax bill the top legislative priority of his second term. The crucial vote came on a motion to recommit the bill to the conference committee, an action that doubtless would have killed it. That motion was rejected, 268 to 160, a larger margin than most lawmakers had expected.

The Reagan Administration has begun discussions with Colombia, Ecuador and Peru about sending American military troops to aid in drug eradication there, Justice Department officials said today. The officials, who termed the discussions ''preliminary,'' said that they could lead to joint antidrug exercises similar to one started in mid-July by the United States in Bolivia. Meanwhile President Reagan said today that he favored broadening his antidrug campaign to eradicating drugs being grown in other countries by vowing to mobilize ''an international commitment'' to win a war against illegal narcotics. Meeting With Envoys Set Mr. Reagan told the National Fraternal Congress of America, a group about 100 nonprofit, civic and community organizations, that he and his wife, Nancy, would meet on Oct. 6 and 7 with United States Ambassadors to countries whose cooperation was being sought to combat illegal drugs.

A Federal prosecutor charged yesterday that ''killing was one way to climb the ladder of success'' in the Gambino crime family and that John Gotti, while in his 30's, helped kill a man to win a ''place of favor'' in the organization. The prosecutor, Diane F. Giacalone, made the assertion in her opening statement in the Federal racketeering trial of Mr. Gotti - now 45 years old and the reputed boss of the Gambino family - and six co-defendants. But Mr. Gotti's lawyer, Bruce Cutler, said Mr. Gotti was being unfairly portrayed, and he asserted, ''The only family John Gotti knows is his wife and children and grandchildren.'' 'Organized Like a Business' For 90 minutes, Ms. Giacalone described the structure and workings of the Gambino organization.

A picture caption in Sports Pages yesterday with an article about the Mets misidentified a player. He was Wally Backman, not Kevin Elster.

Charging that the city has ''dumped'' thousands of homeless people in their neighborhood, a coalition of midtown Manhattan merchants and residents filed suit yesterday to stop further placements of homeless families in an area of midtown. At the group's request, Judge Francis N. Pecora of the State Supreme Court in Manhattan issued a temporary restraining order forbidding the city from housing any more homeless families in the area. But the order was later overturned by the Appellate Division. The lawsuit charges that in placing homeless people in midtown, the city has disregarded the effects on the community.