Virginia's troubled community college system inflated student enrollment figures by about 1 percent last year because of poor management practices, a state audit reported today.

The Virginia Council of Higher Education report said that the errors cost taxpayers $750,000 in unneeded state payments to the schools. Some school in the system counted students twice and wrongly included students who had withdrawn from classes, those who were not receiving academic credit for taking courses of senior citizens who received free tuition at the schools, the audit said.

The report said that the enrollment figures from one campus, Southwest Virginia Community College in Richlands were so inaccurate that they must be completely revised and that the enrollments at five other schools must be checked.

Northern Virginia Community College, the system's largest school, with 31,000 students, improperly reported 70 to 75 auditing students, according to the report. But the college was among 17 where the audit said problems were not significant enough to justify revising enrollment figures.

Enrollments are crucial in determining how much state money the colleges receive. Each student is worth about $1,500 in state funds under the current state budget.

The report emphasized it found no evidence of deliberate enrollment padding at any of the schools. "No school was going around copying names off tombstones or out of the phone book," said Gordon K. Davies, council director. He estimated that enrollments in the entire 23-college system were inflated by about 500 students. The system has 55,000 students statewide.

The report blamed the enrollment errors on "considerable confusion . . . variation in practice and deviation in policy" in the state's sprawling community college system. It said many schools used their own student registration rules rather than the complex ones estalished by the state's community college board.

It also blamed mechanical breakdowns and other problems in the board's computer system for contributing to the errors.

The community college system has come under fire in recent months for alleged financial mismanagement. The system's founder and longtime chancellor, Dana B. Hamel, left office in June after it was revealed that he had suppressed internal audits showing a series of irregularities, including possible enrollment padding.

But yesterday's report, which put total overreporting at about 500 students of the system's total of 55,000, suggested the problem may be considerably less severe than Hamel's critics charged.

Hamel's acting succesor, Richard J. Ernst, who is president of Northern Virginia Community College, called the report "an extremely good one." He told a meeting of the higher education council, "We plan to study its recommendations seriously and make a formal response within a few weeks."

The administration of Gov. John N. Dalton cut the community college system's $120 million annual budget by $6.8 million this year after the board reported enrollment had fallen nearly 12 percent short of projected levels. But the budget cuts are expected to have little impact at Northern Virginia Community college, one of the fastest growing schools in the state system.