CONGRESS RETURNS from vacation to the same intractable math from which it fled a month ago. To finance the tax cut they want to give, the Republicans would have to make much deeper spending cuts than even many of them are prepared to vote for -- or should vote for, given the harm that would be done.

The president plans to solve part of the problem. He has said he will veto the tax cut as soon as it is sent to him. But then what? The GOP leadership has been trying to keep the appropriations bills for the fiscal year that will begin in three weeks within the limits that the financing of the tax bill would require. Partly because of the arbitrary nature of those limits, only two of the 13 bills, both minor, have been cleared for the president's signature. The House has been able to pass nine others, and the Senate its version of seven, but only by making heavy use of accounting gimmicks.

The census has been declared an emergency. No matter that, as the Constitution requires, it has been carried out every 10 years for more than two centuries; the emergency designation means that its cost of more than $4 billion next fiscal year won't count against the appropriations caps. To avert sharp cuts in the early bills, billions of dollars also have been "borrowed" from what it is expected to be the final bill, the big one for the departments of labor, health and human services and education. The Republicans hope that the president will join if not lead them in making this money up. Then part of the blame for breaching the caps can be shifted to him.

There has to be an eventual deal on appropriations, or the government ceases to function. Some people in both parties, including some in the White House, hope the deal can be broadened to include a smaller tax cut than the Republicans have proposed plus a Medicare drug benefit such as the president has urged. But it's not clear the money exists even for those. They would compound the serious long-term fiscal problems that the current surplus only masks. The largest of these is the projected cost of Medicare, which the drug benefit would increase. A drug benefit ought not be added until a plan exists to make Medicare whole. Better they fail to cut a deal, in which case whatever surplus develops will automatically be used to pay down debt.

Both houses also are scheduled to vote this month on campaign finance reform, which ought to pass but which the Republican leadership will try once more to deflect. The House leadership is trying to deflect a strong managed care bill as well, by keeping uneasy Republicans aboard a weaker one. The Senate already has passed one over Democratic opposition that is weaker still. There will be at least a debate before the year is up over extending the main forms of federal aid to elementary and secondary education. Republicans want to give state and local officials greater control over the use of the money. That's less of an issue than it will be made to sound, so long as it doesn't include authority to dilute the amount now spent on the poor.

Democrats want to increase the minimum wage. Republicans have all but conceded it will happen, but it's not clear whether this year or next. Banking deregulation also seems likely, and competing aviation bills are pending; the House version would be a further budget-buster. Gun control may return as an issue if not as legislation worthy of the president's signature. But appropriations, and all the issues they encompass -- from defense and foreign operations to subsidized housing and the budget for Americorps, the president's subsidized voluntary service program -- are what the parties mainly have to deal with. Are they going to cut these programs enough to produce the surplus they would need to finance a tax cut, drug benefit, etc.? We doubt it -- which is why the projected surplus in other than Social Security funds is an illusion. They risk harm by pretending otherwise; they propose to spend money that doesn't exist.