What was going on when I was born?

The ceiling on interest rates for certificates of deposits is to be lifted tomorrow, and banks all over the country will be free to pay whatever they want to attract consumers. The indications are that rates will increase about one percentage point. This will mean, for example, that the rate on the popular six-month certificate will grow to 10 1/2 percent. But introductory rates could climb far higher, as banks compete for the funds. And with federally imposed minimums on such accounts abolished as well, banks will be offering an array of new types of cccounts. The result, at least at first, is expected to be long lines of confused customers at bank branches around the country.

Congress completed action tonight on landmark legislation that would authorize the continued deployment of American marines in Lebanon for 18 more months. The legislation also declares that the War Powers Act now applies to the conflict in Lebanon. This is the first time the act has been invoked since Congress adopted it 10 years ago, over the veto of President Nixon, as a way of imposing Congressional restraints on the war-making powers of the Presidency. This afternoon the Republican-led Senate adopted the resolution in a 54-to- 46 vote that was largely along party lines. In less than 10 minutes the Democratic-controlled House of Representatives, which approved a nearly identical version on Wednesday, agreed to accept the Senate bill by a vote of 253 to 156.

SLIDE into the saddle, slip your shoes into the stirrups and dream of reaching for the ring - fall is a wonderful time to gallop off to nowhere on a carousel. This weekend, stout rainbow-color stallions and ornate jeweled jumpers will make their rounds on more than a dozen historic carousels that are all within about 90 minutes of Times Square. With their painted ponies and tooting mechanical organs - never call them calliopes; organs have pipes, calliopes have whistles - these carousels are flashy reminders of the days when the metropolitan area was the carousel crossroads of the world. They somehow manage to be gaudy and graceful at once, a cross between two incongruous worlds: the cushiony pomp of a vaudeville theater and the ordered elegance of an equestrian pageant. But whether you bounce in the saddle like a Texas cowpoke on a bucking bronco or sit straight and stiff like a riding master, a jaunt on a carousel is more than just five minutes of going around in a circle. Carousel enthusiasts insist it is a trip to another era, a time when craftsmanship mattered. Those are not just wooden horses, they say; those are intricately carved statuettes that have become pieces of folk art and command thousands of dollars at auctions.

A Pentagon official who disclosed wasteful military contracts in 1969 testified today that the Government was still often paying inexcusably high prices and getting ''horrible quality'' in return. The official, A. Ernest Fitzgerald, began his testimony to a House subcommittee by recalling: ''Some years ago I made an appearance similar to this and ended up offending the then- largest defense contractor in the United States, the President of the United States, the President pro tem of the Senate and a majority of the whole Congress, along with the rest of the defense industry.'' Mr. Fitzgerald and Adm. Hyman G. Rickover, the retired head of the Navy's nuclear propulsion program, appeared before the Subcommittee on General Oversight and Renegotiation of the House Banking Committee to express their support for a bill to reconstitute the Renegotiation Board, killed by Congress in 1976, a body that had the authority to attempt to recover unjustified or excess profits on Government contracts.

From the four continents to which they had dispersed, from stardom and from unemployment lines, 332 dancers who once appeared in ''A Chorus Line'' gathered last night to share in the performance that made the musical the longest-running show in the history of Broadway. With its 3,389th performance, ''A Chorus Line'' surpassed the mark held by ''Grease.'' Many theater experts say that ''A Chorus Line,'' more than setting a performance record, altered the direction of American musical theater with its use of a realistic book and ensemble rather than individual acting. The show's moment of triumph arrived at 12:45 A.M., when all 332 dancers flooded the stage of the Shubert Theater for the finale, a song called ''One.'' A sustained standing ovation resounded, as it had at the conclusion of a black-tie dress rehearsal in the afternoon.

WITH its vigorous dance rhythms, rustic instrumentation and centuries-old storehouse of Celtic tunes, Irish music is one of the most evocative of Western folk traditions. And at Town Hall tomorrow night, De Danann and Touchstone, two of today's finest groups with Irish roots, will appear together for the first time on a New York stage. The groups have in common female lead singers whose voices lend themselves to pop-rock as well as to traditional material. Mary Black, the latest in a succession of singers who have worked with De Danann, has a pure, ethereal soprano that at times bears a striking resemblance to the country-pop star Emmylou Harris. Triona Ni Dhomhnaill, of Touchstone, sings with a guttural burr that is just as distinctive, and at times she is reminiscent of the English folk-rocker Linda Thompson.

Meeting behind closed doors, a House Ways and Means subcommittee approved a bill today that would protect the tax-free status of almost all employee fringe benefits, from free airline tickets and free parking to merchandise discounts. However, the panel included a new clause that could discourage employers from offering them. The Subcommittee on Select Revenue Measures attached a new nondiscrimination clause that would require that any tax-free fringe benefit offered, for example, to executives, be offered to all other employees. If approved, the bill would end years of uncertainty about the tax status of these fringe benefits, which have become increasingly popular, by writing specific exemptions into law. The Internal Revenue Service and the Treasury's tax staff have wanted for several years to issue regulations that would declare some fringe benefits to be taxable income, but they have been blocked from doing so by Congress.

For the first time since President Reagan took office, significantly more Americans now disapprove of his conduct of foreign policy than approve of it, according to the latest New York Times/CBS News Poll. The survey, taken more than three weeks after the Soviet Union shot down a Korean Air Lines passenger jet and as the strife in Lebanon remained unresolved, indicated that 47 percent of the American public disapproves, for diverse and sometimes conflicting reasons, of how Mr. Reagan is handling foreign policy matters. Thirty-eight percent approves. By contrast, 36 percent disapproved of his conduct of foreign policy in a survey in June and 40 percent in a poll earlier this month. At the same time, Americans expressed distress with the situation in Lebanon. Although the public believes by more than 2 to 1 that the outcome of the struggle there is important to the defense interests of the United States, there is fear of deepening American military involvement in the region and an overwhelming belief that a cease- fire that took effect on Monday will not end the hostilities.

''The Jets moving won't kill New York,'' said Amelia Slattery, boarding a bus on 42d Street. ''New York is culture. Football ain't culture.'' Indeed it ain't, and there was no one to be found yesterday who believed that the announcement that the New York Jets would move from Shea Stadium in Flushing, Queens, to Giants Stadium in the Meadowlands of East Rutherford, N.J., next season spells doom for New York City. ''Still,'' said Norman Darling, a stockbroker, ''it hurts.''

Articles on Sept. 13, 16, 17 and 22 about the American Ballet Theater's financial problems incorrectly described last year's labor dispute. It was a lockout.

In a significant victory for the Boeing Company over Airbus Industrie, the European plane-building consortium, Japan Air Lines announced today that it will buy nine Boeing 767 aircraft for approximiately $560 million over the next five years. The Japanese-flag carrier also said it might buy six additional 767's between 1989 and 1991. The announcement brought an end to several months of intense competition between the two plane builders. The contest was marked by aggressive corporate salesmanship, diplomatic pressure and a behind-the- scenes squabble between two of Japan's most powerful Government ministries, the Foreign Ministry and the Ministry of International Trade and Industry.

Brazil, as such, never appears on the main agenda of the weeklong annual meeting here of the International Monetary Fund and the World Bank. But just as the Mexican economy menaced the annual meeting last year in Toronto, Brazil dominates this one, except more. For the 4,000 to 5,000 bankers circulating through the corridors of the Sheraton Washington Hotel, headquarters of the meeting, the economic decline in Brazil has come as an enormous shock. Last spring the Latin American nation, which is carrying $90 billion in foreign debt, fell behind in making payments on loans arranged just a few months earlier. Until then Brazil had been one of the bankers' preferred borrowers among developing countries, the one they singled out as a debtor economy that worked.