With great enthusiasm, President Reagan has now renewed his drive to push his tax reform bill through Congress. But a tax bill, more than almost any other kind of legislation, is a collaboration among many authors, and the final version will differ significantly from the present one. It's a good moment to consider the directions that the remodeling ought to take and the standards that Congress needs to apply to any tax bill attempting this kind of broad revision. There are five tests that deserve special attention:

Revenues. Let's begin at the beginning. The purpose of the tax system is to raise enough money to run the government. Mr. Reagan's 1981 tax bill has failed that test, and Congress has to be particularly careful that this one raises at least as much as the present law. Supply-side malarkey about the alleged dynamic effects of another tax cut should be dismissed. The present version barely equals the present level of revenue, and any backsliding here would be sufficient reason to abandon it.

Fairness. Traditionally the income tax has taken a bigger share of a large income than of a small one, and that has seemed to most Americans a good definition of fairness. The Reagan bill decreases the tax burden on the poor and near-poor, and that's welcome. But it also lowers the burden, and on a much more substantial scale, for the wealthy. Mr. Reagan's bill would lower the top tax rate on personal income from 50 percent to 35 percent. Why? There's no commanding logic to justify larger reductions at the top of the income scale than in the middle. The president's bill does not meet the test of fairness, and Congress has a responsibility to protect the principle of a progressive rate structure.

Simplification. The administration forfeited its chance to accomplish real simplification when it decided to perpetuate the lower tax rate for capital gains. That lower rate is crucial to most tax shelters, and without it they would have vanished. The right way to handle them -- as the then secretary of the Treasury, Donald T. Regan, proposed last fall -- is to index capital gains against inflation and then tax them as ordinary income. As the administration bill now stands, it does nothing to make your tax return any simpler.

Economic Effects. Here Congress has to give special concern to the devices by which the administration bill would find new revenue to compensate for the lower tax rates. Abolition of the investment tax credit is overdue. Similarly, the administration is right to eliminate the inequities, from one industry to another, that it established with the fast depreciation allowances in its 1981 bill. More troubling is the attempt by the current ill to recapture some of the benefits already distributed, in past years, by fast depreciation. The amounts of money are large, and would be paid mainly by those heavy industries that are already under great pressure from foreign competition. Those are not the places to find the money to pay for the rate cuts.

But much more important than the technicalities of capital cost, the administration bill would put a severe new burden on the fiscal system that supports public education in this country. The quality of the educational system is the primary determinant of the country's economic growth over the long term. By abolishing the federal tax deduction for state and local taxes, the bill would shift resources away from the treasuries that pay for schools and colleges. To add to the constraints on education merely to achieve another federal tax rate cut would jeopardize future productivity in a way that no tax incentives could repair.

Although you have heard the federal tax system denounced as disgraceful and catastrophic by a succession of eminent public figures, its flaws are not fundamental. Neither are the administration's currently proposed reforms profound. While the administration bill contains a number of improvements over present law, its central and driving purpose is another tax rate reduction. The need for that is not obvious. When Mr. Reagan speaks of reform, what he mainly means is lower tax rates. The other reforms have become incidental to that one. If Congress cannot refashion the administration bill to sustain more adequately the standards that apply to any tax law, there will be no very strong reason at the end of the process to pass it.