Nearly everybody associated with government -- active or retired -- knows there is a 7.7 percent cost-of-living (COL) raise due U.S. retirees on Sept. 1. But nobody in government -- including thousands who would like to retire this month to get the pension increase -- knows when the raise will come through.

The 70,000 feds eligible to retire right now, this month, are between the proverbial rock and a hard place. They don't know what to do, because Congress does not know what it wants to do.

In normal times, U.S. retirees -- and all who retire before Sept. 1 -- could expect the full amount of the coming COL raise. And they could expect to benefit from most of the last COL raise. And they could expect to benefit from most of the last COL raise, which went into effect March 1. But the rules are being changed.

Under current law, federal, postal and military retirees are promised COL raises every six months to help them keep up with inflation. But the Carter administraton and congressional budget-cutters want to limit U.S. retirees to one COL raise per year.

In a compromise, the Senate and House have approved legislation that would only provide one COL adjustment this time around. That is, the House would allow retirees the September raise and save money by skipping the March 1981 raise. The Senate plan would have retirees skip the September adjustment, then give them a full catch-up next March.

The plan approved by the House would eliminate the so-called "look back" feature. It permits people who retire to get the financial benefit of most of the previous COL raise. In this case, persons retiring this month would normally receive the March 1980 raise. The House would eliminate the look-back.

In addition, the tougher House bill would prevent people from retiring shortly before a COL raise is due and getting the full amount of it. Under current law, and individual could retire Aug. 30 and get the full 7.7 percent COL increase due Sept. 1. The House bill would hold new retirees to the actual amount of the COL rise that occurred after their retirement date.

One of those two versions will become law. It will be up to a conference committee, composed of members of the Senate and House Budget committee, to decide which bill will be sent the president.

Those Senate-House conferees will take up the COL question after Congress returns next week from the Democratic convention recess. Until then would-be retires are in the dark.

Thousands of them, according to federal personnel offices, are making plans to retire this month if the House bill -- with the September payoff date -- is cleared. If the Senate measure prevails, it will mean the next COL raise for retirees will not come due until March. In that case, many would-be retirees will decide to stick it out for another few months, studying the benefits of working longer and tax breaks -- if any -- by retiring next year.

Until Congress decides how it wants to change the rules, everybody who is retired from government -- and those who would like to be -- have been placed on hold.