Federal and millitary retired pay, now running at $2.6 billion a month, is due to jump at least 4 percent this September unless Congress decides retirees (100,000 in metro Washington) are getting too many inflation raises, and forces them to wait until March 1981 for their next cost of living catch-up.

With one month left to go in the COL countdown, former government and military personnel (or their survivors) are already due a minimum 4 percent inflation adjustment. But the Senate has already approved language that would permanently eliminate the September adjustments, and the House appears willing to go along with the Reagan administration plan to limit retirees to one COL raise a year -- in March.

Lobbyists favoring the twice yearly COL adjustments for former government and military aides hope they can tack amendments on legislation coming up in the House to protect the March and September adjustments. But the outlook is poor.

Military retirees working for Uncle Sam will not suffer any salary offset if Congress trims the number of COL raises for retired personnel. In an effort to save the twice yearly COL raises for all retirees, House Democrats proposed reducing the government salaries of military retirees by the amount of their retired military pay.

Chairman Bill Ford (D-Mich.) says the tradeoff would be equitable and hurt the fewest number of people. "Faced with the choice of cutting the incomes of civil service annuitants or the incomes of 'double dippers,'" Ford said, "it seemed clear that the more equitable option was to eliminate double-dipping."

Ford said that the typical retired military officer now working for Uncle Sam, as a civilian has $44,830 in total compensation, from civilian salary and military retired pay. According to his breakdown, the typical retired officer gets $14,640 in retirement, and $30,190 in civil service salary. The typical enlisted retiree working as a federal civilian gets $8,510 in retired pay and $19,275 from his civil service job, Ford said. The plan to offset military retirees would reduce the average income of retired officers by $14,640 and that of retired enlisted personnel by the average $8,510. Needless to say, the retirees-in-government are up in arms.

Unless Congress backtracks very soon, however, the dual compensation of military personnel is safe and the number of COL raises for all retirees will be cut back to one COL adjustment a year.