Millions of dollars are taken from the federal civilian disability fund each year to pay double and triple benefits to ex-military personnel who qualify for them by retiring twice from the government.

More than 140,000 retired military personnel work in government as civilians. A new study shows that about 11 percent of the federal civilians who retire each year on disability also are retired military personnel eligible for, or receiving, military benefits.

After retiring from the military, individuals can (after five years federal service) retire from their civilian jobs if they have certified "disabilities." sThat makes them eligible for minimum benefits equal to 40 percent of their civilian federal salary, plus all or part of other military benefits, VA or Social Security disability payments.

General Accounting Office investigators have found that a substantial number of ex-military personnel retiring on disability from their civilian federal jobs had retired earlier on disability from the military.

Although the practice is legal, GAO says the federal disability pension system was not set up to pay high-level, dual benefits to military personnel or others already entitled to other federal payments.

Congress liberalized the federal retirement program more than 20 years ago in a "compassionate" move to provide minimum benefits to younger and short-service employes who become disabled before they qualified for regular pensions. Under the system they can get "minimum" benefits equal to 40 percent to pay that regular federal employes would have to work more than 22 years to qualify.

In a just released study of the impact of military retirees on the federal civilian disability program, GAO found some persons retiring twice from government, both times on disability, which earned the double and triple payments.

GAO, the investigation arm of Congress, recommends legislation to tighten up "loopholes" in the minimum pension benefit law, so that it would benefit short-service federal workers who have no other source of income.

The GAO study concentrated on Air Force retirees who make up approximately 37 percent of the military retirees in government. GAO found that between 1976 and 1978 approximately 29,400 people retired from civilian federal jobs for disability, and the 1,202 of them were Air Forces retirees. Based on its study of military retirees who take second careers in government, then leave on disability, GAO said:

That the 1,202 Air Force retirees studied who retired as disabled federal civilians would get an extra $54 million in lifetime pension payments because of their civilian job-related disabilities. Average civilian federal service time for them was just under 11 years.

That the Air Force retirees who also retired on disability from civilian federal jobs average $415 per month in civilian annuities; $655 monthly in retired military and that one group also received monthly Social Security disability insurance payments of $369.38 per month on the average.

That 10 of 56 Air Force retirees who left civilian federal jobs on disability also had retired from the military on disability, and 25 were getting some form of disability compensation from the VA, in addition to disability pensions from their federal civilian jobs.

GAO said that two of the 56 individuals it spot-checked also were receiving Social Security old age or disability insurance benefits totaling $884.60 per month.

Based on an average life expectancy of 16 years, GAO said that the 56 Air Force retirees "will receive during their remaining lifetimes, about $2.7 million more under the guaranteed minimum provisions than actual civilian service would have provided." GAO based its estimate on the asumption that those retirees will get annual cost-of-living adjustments of 6 percent. In 1979, cost-of-living adjustments amounted to 3.9 percent in March and 6.9 percent in September.

In summary, GAO said "minimum disability benefits are being paid to many retirees who are not, in fact, short term federal personnel. These retirees were already in receipt of government benefits from military careers preceding federal civilian service . . ."

It is unlikely Congress will take any action -- at least during the 1980 election year -- to cut back benefits already promised and earned by military retirees who made two careers in government, being disabled at least once.