'IF THIS ECONOMIC plan doesn't jell, where are we going to get the money for anything?"

The speaker is no liberal Democrat but veteran Republican Rep. Joe McDade of Pennsylvania. His is no isolated concern among Republicans as the euphoria following the stunning Reagan victory on the tax cut fades, and the hard reality of revenue losses begins to sink in.

Various alternatives to deal with this looming problem have been raised by politicians and the press, but the most logical option to be pursued by the administration in the next few years has been virtually unnoticed. It is "creative taxation."

"Creative taxation" means novel routes for raising revenues other than the standard personal and corporate income taxes. These include windfall profits taxes, effluent taxes, users fees, excise taxes and sales or value-added taxes. No tax is politically palatable, of course, -- but when you consider the alternatives, these forms of revenue are both the least unpalatable and the most ideologically congruent means for the Reagan administration to avoid economic disaster down the road.

It is, of course, not inevitable that economic disaster in the form of gigantic deficits will occur. Arthur Laffer and Jack Kemp may be right; an economic boom might well fill the government's coffers enough to eliminate the problem of revenue shortfalls. But at least the potential for a large problem exists, and the administrtion by its own behavior acknowledges the possibility. Reporters totaling up economic numbers figure the revenue loss from the tax cut for the next three years to be $280 billion -- while the savings over the same period from budget cuts come to only $130 billion. This result of the $150 billion shortfall is likely to be monumental deficits.

Let us assume, then, Laffer and Kemp notwithstanding, that we are indeed heading for large budget deficits in 1983 and beyond. The administration could simply let them occur, no longer worshiping at the shrine of the balanced budget as Rep. Kemp has said. But the political and economic dangers of several successive years of hundred billion dollar deficits make that course of action unlikely.

More likely -- and a stated goal of the Reagan economic team -- is to propose to cut federal spending far more than it has been cut to date. Last week President Reagan began a review of $75 billion in proposed additional budget cuts next year. But it will be virtually impossible to come up with these numbers while continuing to maintain big increases in defense and fulfill Reagan's pledge to hold the line on existing Social Security benefits. (Remember, the elimination of the minimum benefit is already included in the cuts this year; further cuts in Social Security must come from other elements of the program.)

It is hard to conceive of Reagan proposing or Congress accepting large cutbacks in the projected defense program. It is even harder to imagine Congress slicing more from Social Security or doing such things as cutting Medicaid and food stamps in half. True, Reagan's accomplishments thus far were hard to imagine six months ago. But each additional budget cut from this point becomes doubly difficult. Future cuts of significance must go to muscle and bone, not just fat, and each cut will come that much closer to the 1982 elections.

If the budget-paring approach doesn't come up with enough, a third option is to renege on the just-passed cut -- go back to the American people next year or the year after and say, "Sorry, folks, no tax cut after all in 1984." This, to say the least, is politically unpaltable to the Reagan team. It would signal defeat for their economic plan, and be greeted by cries of betrayal from citizens and corporations, alike.

No easy alternatives, then, among these three. But there is a fourth choice, which is the most likely option to be pursued by the Reagan administration as it begins its search for additional revenues: namely, creative taxation. Among the several alternatives:

1) Windfall Profits Taxes. As part of his bargaining to win on the tax cut, President Reagan pledged in a letter to Democratic Rep. Glenn English of Oklahoma to "veto -- with pleasure" any natural gas deregulation bill with a windfall profits tax attached. But the $10 billion to $30 billion in revenue that such a bill will look mighty attractive by the time a gas deregulation bill works its way around the Hill. With prospects of consumer heating bills doubling, Congress is quite likely to make deregulation contingent on a windfall profits provision, as it did with oil price decontrol. Look for President Reagan to find some means of gracefully uncoupling from his iron-clad veto promise.

2) Effluent Taxes. The "free market" approach to pollution controls, pioneered in Germany, is to eliminate government regulations and impose graduated but heavy taxes on polluters -- we won't prevent you from dumping your effluents in the river, but you'll have to pay a stiff tax to do so. Thus, producers have a choice -- pollute or pay, or find an alternative method of elimination. It is an intriguing alternative to environmental problems -- and a tidy new source of government revenues, estimated at anywhere from $5 billion to $20 billion for a full-scale program.

3) Users fees. The administration tried, without much success, to add users fees to this year's budget on pleasure boat-owners, private plane users, barges that use inland waterways and national park-goers. Expect them to come back with these and similar proposals over the next three years. The proposal to raise user fees on barges is likely to be moved to a high priority legislative item by the administration, precisely because of its promise for adding substantial revenues while also fulfilling Reaganesque philosophical goals.

4) Excise Taxes. Taxes on liquor, cigarettes, airplanes and other selected commodities are convient and, politically, relatively low-cost ways to raise money. Most such taxes already exist, and would only require a percentage increase. A modest program of excise taxes could bring $5 billion to $10 billion a year in additional revenues.

5) Sales and value-added taxes. These are the most controversial methods for raising revenues. Few politicians have forgotten the problems brought on Al Ullman -- now the ex-chairman of the Ways and Means Committee -- when he proposed a federal value-added tax (VAT) idea in an interview last week. But if the deficit problem becomes larger and larger, the sales tax or VAT alternative will become more and more likely, despite administration intentions. As most European countries discovered long ago, there is no better or less painful means of raising lage amounts of revenue. Moreover, in public opinion survey after survey, the American people have ranked sales taxes as the fairest of taxes, far above income or property taxes. And importantly, a sales tax taxes consumption, thus meshing with supply-side economics more than other taxes.

With personal consumption in America running at about $1.7 trillion a year right now, and adjusting for such essential commodities as food and clothing, a simple federal retail sales tax of 3 percent would garner at least $30 billion a year in revenues. Even more would come in with a 2 percent VAT, which is imposed at each stage of production and distribution, and thus is largely hidden from direct public view. While it is true that an astronomical increase in Britian's VAT, to 15 percent, has badly hurt Margaret Thatcher, a truly modest 2 or 3 percent tax would not be nearly so damaging to Ronald Reagan.

Consider the following scenario: a sluggish economy and continuing high interest rates increase federal outlays and depress revenues below the optimistic administration's projections. Attempts to cut defense spending by $20 billion a year or more are quashed by an angry coalition of hard-line conservative Republians and Democrats. Attempts to cut immediately Social Security benefits fall to a broad-based bipartisan coalition. The already implemented cuts in social programs put upward pressure on the remaining social "safety net" programs, like food stamps, and make deeper cuts in these programs impossible.

Out of this combination of pressures, a sales tax or VAT could easily emerge. It would be no piece of cake to enact -- but it would be far less difficult than deeper budget cuts or income tax increases.

None of these creative taxes in inevitable. None is desired by the administration. But if the economic scenario fits the one sketched out above, expect them all to be occupying attention in congressional hearing rooms and column inches in newspapers soon.