An outside audit of the Fairfax County public schools found the potential for millions of dollars in annual savings should officials follow the report’s recommendations, including changes to staffing levels for elementary schools and custodians.

The voluntary state-led audit concluded that the school system, overall, is a model for other districts, with the Gibson Consulting Group identifying just a few areas of “inefficiencies.” The audit, which began in October 2012 and was presented to the school board Monday, included praise for the administration’s bus routing program and well-organized financial services department.

It comes as schools officials are projecting a $156 million budget deficit for the coming academic year.

Among a list of possible areas of savings, the report found that the county’s elementary schools have more office assistants than necessary, with a far higher ratio of students to administrative staff than in county high schools. The county’s high schools have 211 students per clerical staffer, while elementary schools have a ratio of 135 to 1.

By reducing the administrative staffing levels by a total of 170 positions, the school system could save about $9.26 million each year. The report also recommends more office assistants in high schools and to fund the difference with the projected savings.

The audit also found that elementary schools have too many assistant principals. Compared with other school districts, Fairfax County employs nearly double the number of assistant principals that is recommended, according to the audit.

The report suggested that the school system try employing part-time assistant principals at the county’s smaller elementary schools.

Auditors also suggested changes to custodial services, including a recommendation to cut the staff by 174 positions for a possible savings of $8.34 million per year. The report concluded that the reduction in staff could be easily addressed by adjusting work schedules and staffing based on the square footage of the schools.

That finding appeared to surprise some board members. The board hired 19 new custodians this year at a cost of $1 million to assuage principals’ concerns that school cleanliness had declined in recent years during the economic downturn.

The report also recommended that the school system spend in order to save in the long term, including the addition of about $32 million into a reserve by 2017 to purchase new buses. Centralizing management of custodians, for instance, would cost about $5 million during the next five years.

If the board elects to follow through on all of the audit’s recommendations, the school system could save about $10 million in the next five years.

“These are just recommendations — not mandates carved in stone from Richmond,” said John Ringer of the Virginia Department of Planning and Budget.

Schools officials and elected members of the board said the report validates their belief that the school system, Virginia’s largest, is doing a good job of budgeting and planning.

“This report confirms that we have a foundation of programs and practices that focus on strong performance standards,” said Ilryong Moon, chairman of the Fairfax County School Board. “Our Board is committed to dedicating itself to self-improvement and efficiency with a thorough study of these recommendations.”

Superintendent Karen Garza told board members the report would be useful but noted that the audit had made no significant findings. The administration faces projected deficits driven by significant expected growth in student enrollment.