THE TAX bill certainly confronts the House of Representatives with a genuine choice as it prepares to vote today. But the choice is not the one that President Reagan and his Democratic adversaries have been talking about on television.You needed your hip boots to wade through the hypocrisy; tax legislation seems, as usual, to be bringing out the worst in everyone. It is true, as the Democratic leaders claim, that their bill is better -- slightly better -- for people with incomes under $50,000 a year. But it is equally true, and much more important, that both bills are exceedingly generous to people with incomes over $50,000. Both bills take very good care of a wide range of lobbyists, and both contain the exemption to the oil windfall tax -- the most squalid and dangerous of all the cave-ins. Both parties have retrogressed to the economics of the 1920s that relies on concentrated wealth to propel the American economy.

But there's a choice to be made. President Reagan, for his part, did not tell quite the whole story when he spoke of this tax cut as the matching companion to the budget cuts now in the final stage of enactment. Those budget cuts, in the president's reconciliation bill, do not reduce federal spending nearly far enough to bring him out where he says he wants to be in 1984. This gigantic tax cut, by holding down future revenue, is designed to force Congress into further and deeper budget cuts. Rep. Richard A. Gephardt observed that the president's tax bill would require Congress, a little later in Mr. Reagan's term, to make a further choice between cuts in defense or Social Security.

That's very likely. It's also likely that, in the latter half of a presidential term, with elections coming, both administration and Congress would balk at the choice and, as before, they would once again let the deficit soar.

There's nothing wicked or unclean about a government deficit, as long as the government knows what it's doing and is prepared to be frank about the consequences. But not even the most enthusiastic of supply-siders can seriously argue that a rising deficit will bring lower inflation and lower interest rates. Congressmen who vote on these bills need at least to acknowledge the prospect that they create for the country, and for themselves, two and three years from now. No one is entitled to vote for the president's tax bill who is not also prepared to vote for severe budget cuts beyond anything yet proposed.

On that ground, the Democratic leaders' bill -- the one that the president calls the Ways and Means Committee bill -- is preferable. The differences are not as large as the orators like to suggest. Measured by the standards of social equity, they provide no great moral choice. Both will tend, in slightly different degrees, to increase the disparities of income between rich and poor. The president simply thinks that a very big tax cut is, in itself, a fundamentally good thing and that all of the rest of the government's responsibilities will have to be adapted to it. He, at least, is working out of conviction. The Democrats, in their frantic attempts at vote-catching, have made their bill much bigger than most of them think wise, and they have included innumerable cozy deals of which many of them profoundly disapprove. But there's more to tax policy than personal conviction. For those congressmen who consider the greatest present economic menaces to be continued inflation, high interest rates and an instable currency, the Democrats' bill is, by a modest but conspicuous margin, the sounder and more sensible one.