IT'S ALWAYS a pleasure to hear from Sen. Russell Long, the chairman of the Finance Committee and the man who generally has the last word on our taxes. His letter, which we published today, responds to the observations on the current tax bill in this space last Sunday. Although we did not mention him by name, the senator is correct in assuming that he was much in our thoughts. On that occasion we pointed out that the Senate had just voted by a large majority to retain all the benefits for businesses, after discarding the principal benefit for individual taxpayers. ("How like them," as Eeyore the donkey said on discovering that someone had walked off with his tail).

The senator argues that three fourths of the bill's tax reductions would to to individuals. So they would, it you join him in counting the routine and undisputed extensions of the reductions enacted in 1975. What's now missing from the list of reductions is, of course, the $11.4 billion reduction in individual taxes represented by the famous $50 rebate on which President Carter changed his mind.

As for the jobs credit, opinions is divided. Some specialists think that this credit will be only marginally useful. Others expect it to be totally useless. Its purpose is to subsidize jobs by cutting the employer's taxes. The thing probably ought to be passed on the principle that it's better to have something, however dubious, than nothing. But as a practical matter the impact will be, at best, meager.

Sen. Long concludes with the thought that the bill ought to be passed quickly, and there we agree. Taxation is fundamental to the plans of both business and consumers, and prolonged uncertainty over the rates is unhelpful. The bill has been bogged down in more confusion that its rather simple provisions justify.

The Carter administration has recently been talking enthusiastically about the alleged acceleration of the economy, as it attempts to justify its sudden reversal on the rebates. But last Friday the White House published its latest economic forecast - and it turned out to be markedly less hopeful than the outlook only two months earlier. In February, the administration predicted a real economic growth rate of 5.4 per cent this year and an inflation rate for consumers of 5.1 per cent. Now it has revised the growth figure down to 4.9 per cent and the inflation rate up to 6.2 per cent. That means higher inflation this year than in 1976, as well as slower growth. The idea that the American economy is stabilizing itself under present policies appears to be wrong. There is nothing, unfortunately, in the present severely abrogated tax bill that will make any great difference in these trends, one way or the other.