The government has closed a loophole in its stay-in-school job program that mistakenly allowed some agencies to hire post-graduate students who are members of moderate and high-income families for part-time jobs at pay rates doubled those given to genuinely needy students.

President Johnson began the stay-in-school program. It was designed to give work experience and income to students certified as "needy" either by their schools or their state employment agencies. President Nixon, Ford and Carter have continued and supported the stay-in-school program.

It has provided part-time jobs for about 22,000 students and full-time summer employment for about 17,000 students each year. Students got one-year jobs with work a second year if their financial situation had not changed. Most of the students were hired for part-time or full-time work (during the summer) at pay equivalent to Grades 1 through 4 of the federal pay scale. With the new raise, Grade 1 has a beginning annual salary of $7,960. Grade 4 starts at $10,963.

In spot-checking the program, officials found that a smaller number of post-graduate students studying for doctorates have been hired. Most of these hires were in the old Department of Health, Education and Welfare and at the National Institutes of Health here to work on what amounted to research projects at pay equivalent to Grade 9 and Grade 10 of the federal schedule. Those grades pay $18,585 to $20,467 to start.

The Office of Personnel Management ordered tight new eligibility rules for stay-in-school students. The idea is to limit the program to needy high school and undergraduate students. OPM also set to pay limit at the Grade 4 equivalent level in an attempt to make it less attractive to students from upper income families who were somehow certified as "needy" by friendly college certification officers or state employment offices.

Federal officials said they do not know how many graduate students who should not have qualified on financial grounds actually benefited from the program. But they learned of it from several graduate students who complained to agencies that hired them -- and some to members of Congress -- that the pay they were being given at the Grade 9 and 10 level was "inadequate" for their needs.

Officials contacted yesterday said that agencies were alerted to the pending rules change (it became effective Sept. 9) earlier this year. The change requires them to terminate all graduate students working under the program at rates double those intended for needy and young people and designed to help buy school supplies, clothes and food.