PRESIDENT CARTER, having decided to balance his 1981 budget after all, will shortly provide details regarding the cuts. His friends and associates utterly reject the suggestion that he is holding up the list until after the New York primary next week. How could you think such a thing? The administration wants you to know that these cuts are serious matters, requiring much thought and calculation.

While Mr. Carter is sharpening his pencil, he provides an opportunity for others to offer a few suggestions. Balance will require cuts of $13 billion or so in next year's spending, the White House reckons. One large item, $1.7 billion in revenue sharing to the states, is already a dead duck. It doesn't make much sense at a time when most states are running surpluses and the federal Treasury notoriously is not.

Another inviting target is the list of federal subsidies to transportation -- notably the inland barges, the maritime industry and non-commercial aviation. By charging these users the full cost of required services -- navigational aid, for example -- the federal government would save about $2.5 billion next year.

Tightening is needed in some of the decent and necessary social programs that, over the years, have got a bit sloppy. Cheap loans to college students in need are justified; cheap loans to all students are not. It's important to subsidize school lunches for the children of poor families -- but there's no need to issue food stamps to those families to cover those same lunches. Perhaps you think that's a trivial point, but the overlap in those twice-subsidized lunches costs the government $1.2 billion a year. Some of the job-training programs have got too big to be efficient. Unemployment insurance has an irrational trigger that, at times of high unemployment nationwide, provides additional benefits even to people in areas where unemployment is very low. Reducing this kind of overgrowth and overlap in the social programs, and deferring some new initiatives, could save perhaps $5 billion.

Present law raises a wide range of federal pensions in step with the Consumer Price Index. But the CPI overcompensates for inflation. Social Security benefits are now rising much faster than the average wages of the people who are working and paying for those benefits. It's right that people on federal pensions should be as well protected from inflation as the rest of the country. But it's wrong that they should be better protected. Holding the cost-of-living adjustment to 85 percent of the CPI, instead of the present 100 percent, would save $2.7 billion a year. Adjusting the pensions of retired civil servants once a year for inflation instead of twice would save another $800 million.

If Mr. Carter can't find that $13 billion promptly, Congress will do it for him. Amidst all the discussion of Mr. Carter's plans, it's necessary to note that Congress has now seized the initiative in budget planning. The chairman of the House Budget Committee, Robert N. Giaimo, intends to announce on Wednesday his own proposal for a balanced budget. The chairman of the Senate Budget Committee, Edmund S. Muskie, said last week that he could "guarantee" that his committee will produce a balanced budget. The congressional budget procedure now gives those committees the upper hand in fiscal policy and, without bothering to wait for Mr. Carter's views, they are proceeding to enforce his promise of a balanced budget.