Tax time is upon us -- that fortnight when it is customary to grumble about the Internal Revenue Service. The season's spirit was captured for all time, a few years back, by a cartoon showing a police detective standing over the body of a slain IRS employee. The detective asks: "Did he have any enemies?"

Rationally speaking, of course, blaming the IRS for high taxes is like blaming the police for bad laws. The pertinent question is whose dirty work the IRS is doing.

Which brings me to Edward Kennedy. Campaigning in New York the other day, Kennedy charged that Jimmy Carter was going to slash federal aid to New York City. He managed to make this sound like a direct expression of Carter's essential misanthropy: "Carter doesn't care about New York, you see.

It is the first principle of politics, where Kennedy comes from, that when you care about people, you show it by spending other people's money on them. So far Kennedy has been spared anything like Carter's recent and harrowing encounter with the laws of arithmetic. He launched his career in spending, after all, back when Carter was still down on the farm in Plains, and he isn't about to change now. The advent of April 15 is a good time to remind oneself that Kennedy is a leader among those fiscal free spirits who have driven blue-collar workers into what used to be executive tax brackets.

At the moment there is bipartisan consensus, this side of Kennedy, that our wealth is finite, that federal spending is out of hand, that restraint is in order. But there must be a way to see to it that this becomes something more than a transitory mood, some way to capitalize on the moment and turn it to permanent advantage.

One method would be a handy index of congressional spending. Just as the sports pages regularly list the batting averages of big league players, the political pages could find a convenient shorthand expression for each senator's and representative's spending record. The figure might and should be one of recognizably human scale.

For instance: this year's federal budget will be in the neighborhood of $600 billion. That comes to about $3,000 per American. Since many Americans wear diapers or live on the dole, the average taxpayer will in effect buy Uncle Sam a new car. Putting it that way gives the issue a certain pungency it otherwise lacks.

Suppose the average family makes $20,000, of which Senator Blow votes to spend $10,000 on federal projects. If that figure were published beside his name, it would provide a convenient reference point for campaign discussion.

Now that figure doesn't in itself prove that Senator Blow is extravagant. He will have the chance to make his case that $10,000 is something like an optimum level of taxation on a $20,000 income. He may even want to argue that his average is actually paltry in relation to the country's needs. The issue, quite properly, will become one of philosophy. But all discussion would begin, quite properly, with the sheer fact that he is committed to enlarging the public sector, at the taxpayer's expense, to such and such a size.

Few voters would take the simple-minded view that whoever spends least is ipso facto the best congressman. But the spending index would surely tend, on the whole, to reverse the creeping presumption that the national wealth belongs to the government. Its very specificity would make our representatives more self-consciously accountable, and help prevent politics from continuing to swallow up every aspect of our lives.

Taxation is a serious business. It means taking money from people by force, with criminal sanctions if they resist. In our time the taxing power has been used very frivolously, to buy votes from powerful constituencies. The average taxpayer is left defenseless -- not only unorganized, but ignorant of where his money goes. Spotlighting the spenders would force a more scrupulous use of the taxing power, and take some of the trauma out of April 15.