THE POVERTY RATE is back about where it was when President Reagan came to office, but with this enormous difference. Then it was headed sharply up, mainly by virtue of the roaring inflation rates of the latter Carter years; incomes were overmatched by prices. Now it is drifting down, partly because so much of that inflation was wrung out of the economy by the Federal Reserve Board in the first Reagan term.

That major accomplishment is the important good news in the poverty figures just published for last year. It competes for the headlines with what continues to be pretty sobering news as well. On the one hand, the poverty measure is well below the high of 15.2 percent it touched in 1983. On the other hand, at 13.6 percent after four years of recovery, it remains well above the comforting lows of 11.1, 11.2 and 11.4 percent attained at various points in the 1970s. Forget the usual tinny games of credit and blame; the economy seems to have lost important ground.

The overall rate is not the only basis for believing this; there are chronic problems with the distribution of poverty no less than its extent. Too many groups are being left too far behind. The poverty rate for children continues to be a disheartening 20 percent (as against only about 12 percent for the elderly). For blacks it is 31 percent, for black children nearly 43 percent, for Hispanics 27 percent. The richest fifth of all families had 43.7 percent of family income last year, the highest ever, while the poorest two-fifths had 15.4 percent, an all-time low. The gap has been growing for a number of years. It has been calculated that the richest fifth of families had about $40 billion more in income last year than they would have had if their share of family income had stayed the same as in 1980. There are all kinds of reasons; wage deterioration in the lower reaches of the economy, where the minimum wage has not been raised since 1981, seems to be one. The government reports that 41 percent of all poor people 15 years old and older worked last year, the highest percentage in almost 20 years, and about 2 million worked full-time year-round.

The Census figures reflect only cash income, not the in-kind benefits to which the government has increasingly turned in recent years. Counting these -- there are problems with how to value them -- the poverty rates are lower, but the pattern is the same. There's also a gap in this society between profession and performance. It's not as fair an economy as we like to believe.