An outside audit has confirmed the enrollment counts of the D.C. public schools and the city's 31 fledgling charter school campuses but is raising troubling questions about absenteeism and verification of residency at both types of school.

The audit shows an unanticipated increase in the number of students attending the District's taxpayer-funded schools, from about 75,500 last year to more than 77,700 this year. The number includes enrollment for charter schools, which operate with public money but are independent of the school system bureaucracy.

The audit by the District accounting and consulting firm Thompson, Cobb, Bazilio & Associates confirmed the school system's reported enrollment of 70,762 and said the number of charter school students was 6,980, very close to what the schools themselves reported. It is the second year in a row that the firm has confirmed Superintendent Arlene Ackerman's count, after years in which auditors questioned the school system's figures.

What remains unknown is where the new students are coming from. School system enrollment had declined steadily in recent years, and most growth projections anticipate that newcomers will be largely people without school-age children.

School and city officials say they believe some students may be switching from private or parochial schools to charter schools, which are free. They also speculate that some families may be moving into the city to take advantage of new tax credits for first-time home buyers and a new tuition assistance program for D.C. graduates.

"I don't think anything nefarious is going on," said Francis Smith, executive director of the D.C. financial control board. "It indicates some confidence. People think that things are going to turn around."

Smith suggested that city residents are increasingly impressed by the charter schools and by Ackerman's efforts to reform the school system. At the same time, he said, his staff is in the process of checking to see whether some of the roughly 3,000 students kicked out of D.C. schools last year because they lived in the suburbs had resurfaced in city charter schools.

The enrollment numbers could change the amount of funding public schools and charter schools receive. They are supposed to get a set amount per pupil, but the amount allocated is based on last year's enrollment and does not anticipate any increase.

The audit also found extremely high absenteeism at traditional and charter schools. More than 20 percent of students were absent at eight of the charter schools on the day the audit was conducted; at three of those schools, more than 40 percent of students were out. Fourteen D.C. schools reported more than 20 percent of students absent on the day of the count.

Auditors found that 18 percent of D.C. public school students and 16 percent of charter students had failed to submit the required three documents to prove that they live in the District.

Smith said the control board is extremely concerned about absenteeism and proof of residency. A spokeswoman for Ackerman said the superintendent has asked her staff for reports on both issues.

Ackerman has cited the families of special education students for whom the city pays private school tuition as especially lax in proving where they live. But officials at one such school, St. Coletta School in Alexandria, said the school system lost proof submitted by some students, failed to properly notify others of what was needed and made other significant residency-verification errors.

The school system has threatened to stop paying private school tuition for students--many of whom were placed in private schools as a result of suing the city--if they had not proved residency by yesterday.