WITH A THIN combination of political grandstanding and financial nitpicking, D.C. Council Chairman David Clarke has proposed a little government giveaway plan. He discovered that city revenues have come in slightly above the Barry administration's original projections -- by an amount equal to about 2 percent of the municipal budget. He has seized on this fact to excoriate the mayor for coming up with a surplus and to suggest a $25 rebate for every taxpayer. Whatever other financial management difficulties the administration may be experiencing these days, the existence of a relatively small and probably fleeting surplus of cash is hardly an indication of bad tax policy.

On the contrary, the money can be used for important purposes, as Mayor Barry has proposed: for summer jobs for youth, public housing repairs and drug abuse prevention programs -- the very kinds of projects that Mr. Clarke has strongly supported over the years. This makes more sense than buying the chairman's version of a drug store rebate plan. And if there turns out to be yet more money left over, the city could always make another payment on its long- term and mostly inherited budget deficit -- just as the council has been advocating with admirable consistency for the last few budgets.

At best, revenue projections by any local government are imprecise, since the yields are affected by what's happening to the national economy as well as by federal tax policies, consumer spending attitudes and the real estate marketplace. Unless Mr. Clarke can pinpoint projections more sharply than the city government has, he should be relieved that Mr. Barry's tax policy has produced revenues on the high side of the mark. It beats red ink.