THE CONGRESSIONAL Budget Office pointed out last week that President Carter's chances of balancing the budget by 1981 are pretty close to zero. His chances of getting unemployment down to his recently adopted target of 4 per cent by 1983 are about the same and; of course, the two goals are inconsistent with each other. Further, the CBO calculated, the tax cuts necessary over the next two years will be larger than the administration has yet suggested.

But these pointed observations made no great stir. The reason was, no doubt, that the CBO has given Congress plenty of warning over the Past year of the realities of the budget and the prospects for economic growth. That is the CBO's job - to provide Congress with economic counsel that is both sophisticated and independent.

Such information is one of the elements of power, and the White House formerly had something close to a monopoly of it. There was no congressional counterpart to the President's Office of Management and Budget. But in 1974 Congress established the CBO. It was the product of deep congressional suspicion of President Nixon, and the Democrats' well-justified accusations that his administration had repeatedly misled them on the economic outlook.

Since the arrival of a Democrat in the White House, the CBO - and the concept of congressional independence that it represents - has been undergoing a subtle test. With unemployment high last winter, Democrats in Congress began clamoring for huge public-works appropriations. When the Democratic leadership came up with a whopping proposal, the CBO coolly pointed out that the government could not possibly spend that much money this year. Simultaneously, the CBO reports cast a heavy shadow on the new President's promises about budget balancing. Administration loyalists in Congress began to complain.

The outcry reached a crescendo in June. Two committees had directed the CBO's director, Alice Rivlin, to study the President's energy program. The study concluded that the program would conserve substantially less oil than Mr. Carter had claimed and, as Mrs. Rivlin noted, there was not much evidence of the public sacrifice of which he had eloquently spoken. Some (although not all) of the House leaders vehemently denounced Mrs. Rivlin for meddling in politics. For a time, there seemed to be a real question whether a Democratic Congress, working with a Democratic President, really wanted independent analysis.

But, over the summer, the basic geometry of Washington politics began to reassert itself. Most of the time, in most issues, the basic division in government is not between Congress and the White House. Even the most loyal of the President's friends in Congress were reluctant, apparently, to return to anything like the old custom of taking the President's numbers on faith. The character of the CBO's latest economic projections indicate that Congress is firmly sticking with its original 1974 decision in favor of independent counsel. Clearly that's the right choice. In matters of economic policy, two computers are better than one.