THE MAN from Mars came orbiting through the office yesterday, and asked why the House Ways and Means Committee is repealing the corporate income tax. Nobody on Earth would ask a question like that. The Martian gets out of touch on those long voyages through the sidereal night.

We explained that the Ways and Means Committee wishes to promote American prosperity. The corporations have assured the committee that cutting their taxes will make the country more prosperous. Since that's true, the committee reasons, why not go whole-hog, abolish corporate taxes altogether and embark on a new era of infinite prosperity?

One must not exaggerate, we cautioned. It is not quite correct, technically, to say that the committee intends to abolish the corporate income tax entirely. A certain vestige would remain.

"Any corporation paying taxes under the committee's proposal ought to fire its accountant," said the man from Mars. That's doubtless true, we acknowledged, but it always take the accountants a while to get used to new rules. The committee is putting its faith in inefficient accountancy -- at least until 1984 when, the nation has been assured, the budget will come gloriously into balance.

The Martian has a deep interest in the American two-party system. We explained that, last winter, one party proposed a huge tax cut emphasizing mainly rate reductions, across the board, for individuals. The other party is now responding with demands for more highly focused cuts. First, it wants immediate reduction of the top individual rate from 70 percent to 50 percent. Then it proposes cutting the corporate rate from the present 46 percent to 34 percent and, meanwhile, abolishing all taxes on re-invested profits.

Why, asked the Martian, did they simultaneously want to cut the corporate tax rate and abolish taxes on re-invested profits? He is a bit slow about these things. It's simple, we said. The committee intends to encourage business investment.

"Wait a minute," said the man from Mars. "If you want to increase business investment, you'd do much better to increase the corporate tax rate instead of dropping it. That would make your investment deduction worth much more to the corporations. It would put them under real pressure to re-invest profits, instead of passing them out in dividends to the shareholders." He was technically quite right, we acknowledged.

"So why dosn't the committee do that, instead of reducing the corporate rate and undercutting its own intention of raising investment?" That's another question that only a man from Mars would ask in Washington this summer.

The man from Mars looked over his notes and said, "Well, it looks to me like the usual lineup -- one party pushing from broad cuts in personal taxes, the other one trying to take care of business and the corporations. I Can't see that much has changed." Perhaps nothing fundamental, we condeded.

"I keep forgetting," the man from Mars said. "Which party is it taht you say controls the Ways and Means Committee?"