What was going on when I was born?

The income tax filing season is when many working spouses rediscover a costly fact of American life: The state of matrimony is not a tax haven. The tax tables are designed in such a way that two-earner married couples generally pay a higher tax than they would as single taxpayers. This ''marriage penalty,'' however, will be lessened this year by an increased special deduction that Congress enacted in 1981. The marital deduction has been doubled, starting with the 1983 tax year, to a maximum of $3,000, from $1,500 on 1982 returns, when the provision first took effect. The deduction, while alleviating the marriage penalty, does not eliminate it.

The Reagan Administration said today that it was urging President Amin Gemayel to move quickly to form a new Government that for the first time would include key representatives from Lebanese factions that have been opposed to his policies. Senior American officials and diplomats here and in the Middle East were reported to be working around the clock to limit the damage caused by the resignation of Prime Minister Shafik al-Wazzan and the rest of the Cabinet and by the fighting in Beirut between Shiite and Druse militia forces and the Lebanese Army. Administration Shows Concern There appeared to be no effort to disguise the Administration's worries that the situation might deteriorate further, but senior officials sought to make the best of the situation by suggesting that a new, stronger Lebanese government might emerge if Mr. Gemayel showed enough political finesse. Some officials expressed concern, however, that Congress might look on the situation in Lebanon as having deteriorated so badly as to warrant an immediate withdrawal of the 1,800 American marines. A pullout is being advocated by Democrats in the House of Representatives and is being resisted by the Administration, which does not want to give the impression of being forced out of Lebanon.

Bishop John J. O'Connor of Scranton, Pa., who was chosen by Pope John Paul II last week as the next Archbishop of New York, has a reputation among fellow bishops as an expansive, articulate prelate who is persuasive and utterly loyal to the church's teachings. Last August, Bishop O'Connor detailed his thinking on many subjects of concern to the church, from the role of women to preaching from the pulpit, in a 23-page letter to priests in his diocese. Bishop O'Connor emerges as a solid backer of church doctrine who is concerned with carrying out Catholic teachings and canon law. He urges priests to be steadfast and confident about the authority of church dogma, introduces policies intended to help in such areas as the annulment process, and emphasizes a strong hierarchical view of Catholicism. Bishop O'Connor's tone conveys enthusiasm and assurance in addition to a strong sense of his authority as a teacher. In these excerpts, the bishop shows a sense of strong resolve and determination, defining the role of various elements in the church including priests, lay teachers and nuns.

''Some efforts should be made to end these bloody events where innocent people are killed and homes are destroyed while all hope is lost.'' - Shafik al-Wazzan, resigning as Prime Minister of Lebanon. (A1:6.)

Because of an editing error, an article last Wednesday about the new Archbishop of New York misstated the number of archbishops who preceded him. There have been seven.

Except for the buzz and click of neon lights, 42d Street was still. Shortly after midnight, a blue sedan with the New York City seal on its doors pulled onto the street from Second Avenue and headed west at a crawl. The three men inside rolled down their windows and began listening. ''Not bad,'' said Frank Cecora, as the car passed Seventh Avenue. Since 6 P.M. Mr. Cecora and the other men in the car, Stephen O'Connell and Albert Higgins, had been cruising the streets of Manhattan in search of noise and air pollution.

The Islanders today completed a weekend sweep of the Pittsburgh Penguins. The 5-4 victory, which came after the Islanders had snapped a 5-game losing streak Saturday night with a 6-5 triumph at home, put the team back in first place in the Patrick Division, a position that they have been trading with the Rangers almost daily. The Penguins, with the worst home record in the National Hockey League, have lost 14 of their last 16 games. The Islanders salvaged today's victory with 3 minutes 35 seconds to play when John Tonelli was credited with a goal after a shot by the defenseman Tomas Jonsson, who scored 2 goals and had 2 assists, bounced off him into the goal.

After three years of slumping car sales that saw almost 4,000 auto dealers go out of business, the mood at the annual convention here of the National Automobile Dealers Association is decidedly upbeat. ''The attitude around here is completely different from the last few years,'' observed William J. Symes, a Los Angeles-area Cadillac dealer, after a day of slapping backs and shaking hands at the sprawling Convention Center. ''There's nothing like a little profitability to improve people's outlook.'' William C. Turnbull, the outgoing president of the association, remarked: ''You can see the recovery in the attendance. There are people here now who haven't been able to come for several years.'' Officials said attendance at the three-day gathering is expected to total 15,000, up from 12,000 in 1983 and a low of about 10,000 in 1980.

Thirteen years ago, when the first $2 bet was wagered, offtrack betting looked like a sure winner for New York City. But rising overhead costs, declining customer interest and changes in the formula for distributing profits have turned what was considered a safe gamble into a risky venture for the city's Offtrack Betting Corporation and five other OTB's in the state, according to state and city officials. Although the six corporations had total wagers, or a handle, of $1.5 billion last year, their revenue to the city and other local governments has been steadily declining. From 1979 to 1982, the last year for which there are available statistics, payments by the corporations to the localities dipped from $113 million to $101 million, according to the state's Racing and Wagering Board. New York City has experienced the sharpest drop in OTB payments - from a record $65.3 million in 1980 to $50.6 million in the fiscal year that ended last June.

Western diplomats here say that Nicaragua's Marxist leadership is still on a path leading to multiparty elections in 1985 despite the Government's announcement Saturday that it had postponed indefinitely an important step toward elections. But the diplomats say that at the same time Nicaragua hopes to force the United States to accept its legitimacy without giving up significant power to democratic opposition groups. The officials - both American and Latin American diplomats and some experienced Nicaraguan political authorities - assert that a combination of economic, military and political pressures are pushing the country's nine- man Sandinista military directorate to hold elections for the presidency and a constituent assembly next year. In announcing Saturday that it was postponing the promulgation of electoral laws, the Nicaraguan Government cited rebel air attacks Thursday and Friday that it said had been ordered by the United States. But in Brazil today, Secretary of State George P. Shultz offered a different opinion, saying the postponement was ''a transparent device to back away from elections.'' (Page A8.)

T HE rink on Williams Lake, behind the LaFontaine home in Waterford, Mich., is out of operation these days. There are no more pick-up games after school, or late-night skates under a floodlight. Family reunions, with Grandpa Fred LaFontaine tending goal, magazines taped under his pant legs, have been disbanded. The LaFontaine brothers, Pat and John, are in their teens and playing elsewhere. ''As the boys grew older, the rink grew and grew,'' said their mother, Giselle LaFontaine. ''Their legs got longer, their sticks reached out further. . . it was such a popular place. It's funny to see no one out there now.''

A target balloon released from the space shuttle Challenger today burst into shreds, forcing the astronauts to curtail a critical rehearsal of rendezvous maneuvers for making repair calls on orbiting satellites. It was the second serious mishap to strike this mission, which had already suffered a malfunction that sent a communications satellite into the wrong orbit Friday after what had seemed a flawless launching from the shuttle's cargo bay. Engineers reported today that they had found the satellite and it appeared to be in good shape, but probably would never be usable as a communications relay because it is out of position. Westar Cannot Be Retrieved The National Aeronautics and Space Administration said that although the shuttle was designed to retrieve and repair satellites, the Westar was not built with the grappling fixtures necessary for retrieval because it was supposed go into orbit far out of the shuttle's reach. The satellite malfunction initially forced a one-day delay in the launching of a second communications satellite, the Palapa B-2.