THE BUDGET farce continues. The latest episode has House Transportation and Infrastructure Committee Chairman Bud Shuster seeking a bye for highways and aviation from the across-the-board budget cut that Republicans are proposing in the name of protecting Social Security. Mr. Shuster yields to none in his devotion to fiscal discipline, but surely the budget rules were never meant to apply to the programs under his jurisdiction.

For fear the chairman's defection could defeat the across-the-board cut--he has about a sixth of the House on his swollen committee--the Republican leadership was struggling yesterday to find a way to accommodate him without opening the door to other byes. There was talk of a deal in which he would be given a chance to recoup next year what he gave up this.

The dispute should be the easier to resolve because the across-the-board cut is itself for show. The president has rightly vowed to veto it. Then arguments will ensue about which party did or didn't use part of the Social Security surplus once again this year to finance the rest of government. The Republicans will say triumphantly that the Democrats did it when they rejected the across-the-board cut. But the triumph is doubly silly. Congress has long been on course to spend at least a fifth of this year's Social Security surplus--some $30 billion--for other purposes. It has gone to elaborate, gimmicky lengths to mask the fact, either by not counting spending or by kicking it over into next year. But no one is fooled, least of all the voters whom the gimmicks treat with such contempt--nor is Social Security the least bit harmed. The same IOUs are put in the trust fund whether the surplus is used to finance other programs or pay down debt, the alternative.

The president, meanwhile, to refurbish his own credential as a protector of Social Security, has revived and sent to Congress a "reform" proposal that does little more than make explicit an already implicit commitment on the government's part to eventually use general revenues to help cover Social Security's costs. The long-term gap between costs and available revenues remains. Neither party has a plan for saving Social Security. They have plans only to invoke the program in the next election. They are fighting about the details of the unreality they are trying to foist off on the public as real. That's the playing field on which Mr. Shuster continues to seek advantage, and perhaps will be granted it.