A beleaguered congressional Office of Technology Assessment has become threatened by the same budget as Congress often uses on executive agencies it accuses of overspending taxpayers' money.

The 6-year-old OTA discovered two months ago that it was spending at a rate that would put it $1.8 million above the $11.2 million it was authorized this fiscal year.

"It was like a rocket, which usually gets a midcourse correction halfway to target," said John Gibbons, incoming OTA director. "This time, the halfway point came between the time Russ Peterson [the outgoing director] left and I got there and the correction fell between the cracks."

Basically, Gibbons explained, the OTA committed itself to too many long-range projects. About 40 projects had been started and allowed to continue, some for as long as five years. The result was that too many people ended up spending too much money.

The first outcome was that the House Appropriations Committee cut OTA's fiscal 1979 budget from $11.2 million to $9.4 million, forcing Gibbons to make drastic changes to keep OTA afloat.

Gibbons immediately halted work on a study of the "risk to society" of holding back development of technology, even though 70 contractors had bid on directing the study. The move saved $260,000.

The new director also cut back studies on genetics and energy alternatives, then halted a study of the Department of Energy's national laboratories "that had been going on for almost five years without producing anything." Next, Gibbons killed a study of food technology for developing countries and three parts of a four-part study on disease prevention.

"What I did was to defer as much as I could of this year's work to next year," Gibbons said in an interview yesterday. "I basically mortgaged this year's funds until next year."

Next, the ax fell on people, Gibbons reduced the number of OTA "fellows" from six to four. He told three staffers there may not be any work for them when their projects end in October.

Gibbons eliminated the staff of four doing "exploratory" work on new projects. Then, he fired 14 people whose average salaries of $30,000 a year meant a savings of $420,000 a year.

"If things had gone ahead, we'd have been way over budget," Gibbons said. "We had to lay off people and eat some problems; that's all there was to it."

That is not all there was to it, say some of the people who are being laid off. They say that as late as June 20, two weeks before things began to fall apart, the staff was being urged to spend more money because it was underspending its budget. They also say that at least two overruns in energy studies cost OTA more than $1 million in the last year.

If it all sounds like what Congress says when it criticizes executive agencies, so be it. In a familiar-sounding footnote, Gibbons will now take his hat in hand and approach the Senate Appropriations Committee to ask it to restore the $1.8 million cut by the House.