The House is moving toward legislation that would trim - but not eliminate - dual payments that now go to more than 141,000 retired military personnel who work as federal civil servants.

Insiders expect the House Investigations Subcommittee will come up with a compromise bill that will reduce "double dipping" (the practice of drawing both pay and pension checks from the government) without cutting off pension benefits earned by former military personnel.

Opponents of double dipping argue that it is unfair and too costly for the government to give military retirees full pensions and full civil service salaries when they begin second careers with government. Under the law retired reserve officers and all retired enlisted personnel keep all pension, and draw full pay when working for the government.

Retired "regular" officers, however, are limited in the pensions they can draw while working as civilians for Uncle Sam. Under the current formula, they get the first $4,045.16 of their pension, plus one half the remainder - in addition to full civilian salaries - when they take jobs with the government.

Backers of dual compensation say the military retirees earned their pensions, and should be free to work for anybody - including the government - without financial penalty.

The Investigations Subcommittee, headed by Rep. Robert N.C. Nix (D-Pa.), has been hearing arguments on dual compensation, and will have its final hearing Sept. 23. At that time, spokesmen from Defense and the U.S. Postal Service (the two biggest employers of military retirees) will testify, as will brass from the Civil Service Commission. The CSC people will speak for the White House.

Nix is chairman of both the Investigations Subcommittee and its parent body, the House Post Office-Civil Service Committee. Whatever legislative course it takes - and the committee is divided on the issue - will be presented to the House in early 1978.

At the moment, the Nix unit has several major options. Among them:

Do nothing.

Order a complete cutoff of military retirement pension benefits for retired military personnel who take jobs with government in the future. This would leave unaltered the pay and pensions of the 141,000 on-the-job retirees.

Cut off pension payments for all military retirees including those now working and those who join government in the future for as long as they draw a civilian federal paycheck.

Compromise by limiting the pay of military retirees who come into government based on their military pension. In other words, a retiree might be able to draw his full $10,000 pension but his civilian salary would be reduced accordingly so that he would get no more for working than a regular civil servant in the same job.

Nobody knows what course the subcommittee will take. But it is a good bet that it will come up with a compromise that will preserve the earned pension of the retirees, while trimming their civilian salaries. Much the same thing is already done with retired civil servants who are re-hired by the government.

There also is a good chance the subcommittee and committee will come up with legislation that would whack the income of more than a dozen retired generals and admirals now working as federal civilians.

Committee investigators say that some high-ranking military retirees earn $70,000 to $80,000 a year - in combined pay and pension - and they believe that this is out of line. A decision is expected within the next couple of weeks.