In the recent budget debates, the Reagan administration demonstrated that it aims to hold down spending on programs other than national defense with ample cuts in welfare, food stamps and Social Security. But, at least one program has eluded the scalpel. That is a program on which we will spend $13.8 billion this year and $1.6 billion more than that next year if we take no action to hold costs down. I'm talking about military retirement.

To put this in perspective, $13.8 billion is $3 billion more than we spend on food stamps and nearly twice as much as we spend on the Aid to Families With Dependent Children welfare program. But military retirement is paid neither to the indigent nor, in most cases, to the retired. The average military careerist leaves the service at the age of 42.3 years (not including disability retirements) and goes on to a second career and a second income while collecting his military pension.

An interesting point about military retirement is that the president doesn't have to go to Congress to hold down escalating costs. He has the right, by law, to contain them right on his desk.

Military careerists begin flocking to the retirement rolls and collecting immediate pensions as soon as they reach 20 years of service. But contrary to public opinion, nothing in the law makes retirement after 20 years a right. Federal statutes provide an absolute right to military retirement for officers after 40 years in uniform, or after 30 years for enlisted personnel. The law clearly states that retirement with as little as 20 years of service is only available at the discretion of the president or the secretaries of the services.

The House debated these early retirement provisions in July 1935, and dealt specifically with the section of the statutes that reads that a serviceman with less than 30 years of service "may, upon his request, be retired." Rep. John Henry Hoepple (D-Calif.) vocally opposed the bill, and floridly described it as a "distinct raid on the Treasury of the United States."

Hoepple, who has served 23 years in the Army as an enlisted man, denounced the bill that provided early retirement for officers only as "pork barrel" legislation. "Why vote more 'port' for the already overprivileged class," he added.

A clearly angered Rep. Charles L. Faddis (D-Pa.) responded, "There is nothing of the kind in the bill." He said retirement with less than 30 years of service "is at the discretion of the president. So that [pork] argument is wiped out." But Hoepple kept up his attack.

Rep. Matthew Dunn (D-Pa.), a blind congressman elected in the Democratic landslide of 1932, like Faddis and Hoepple, also pointed out to Hoepple that early retirement was not open-ended, but depended on the discretion of the president. Hoepple interjected, "But the president always does what the War Department tells him to do."

Dunn replied, "I doubt whether the president of the United States would retire any man at the age of 37 unless he had a very good reason."

But presidents do retire men and women at the age of 37. Last year alone, 1,744 servicemen and women retired at the age of 37 and began immediately to collect their pensions. As the congressional debate shows, Congress clearly didn't intend that early retirement should be the norm, but the discretionary authority to grant retirement after 20 years has been converted into a virtual rubber stamp.

The Reagan administration finds itself in a unique position. It can take a major step toward trimming federal spending on its own initiative, without having to battle it out with Congress. And the budgetry implications are potentially large. From a figure of $2.8 billion in 1970, the 1982 budget will pay out $15.4 billion for military retirement.

I am not suggesting that no one should be allowed to retire short of 30 years. I am saying that early retirement should no longer be treated as an automatic right.

There is concern, of course, that any tampering with retirement benefits will undermine the all-volunteer force and prepare the ground for a return to the draft. We have to remember that the draft would be used only to get young people into the service. Pensions are the farthest thing from the minds of potential 18-year-old enlistees. So a change in retirement won't make a dent in enlistments.

Changing the retirement provisions could discourage some people with 10 or 12 or 14 years in uniform from staying. However, thousands of competent officers and enlisted men who want to stay in uniform are now being forced into retirement after 20 years. By lengthening careers, we will probably pick up as many people who want to stay in uniform as will drop out early from dislike of the career.

I know of officers approaching the 20-year point who mark the remaining days off a calendar while doing as little work as possible. We would be better off to keep people in uniform after 20 years who want to be there than to induce those who hate the job to stay until 20 just for the generous pension.

The president and the secretaries of the Army, Navy and Air Force should exercise the authority given them in Title 10 of the U.S. Code to expect longer periods of service before putting military careerists on the pension rolls.

We are clearly violating the spirit of the law. Congress wrote the provision with no expectation that thousands of youthful, skilled and healthy careerists would fill the retirement rolls. What's worse, the lengthened military career fits right in with one of the Reagan administration's declared goals -- lengthening the working careers of Americans. The administration's main Social Security proposal calls for reducing the benefits paid early retirees -- age 62, in that case, by more than 40 percent in order to induce people to work longer. Why not longer careers in the military, too?