When DeKalb County school officials combed through financial records over the weekend, they made an astonishing discovery: The district has millions more dollars than they’d thought.

Revenue that had gone unnoticed within those pages stared back at them. The windfall is only projected but can still buoy the bottom line for next year’s budget, Superintendent Michael Thurmond told stunned school board members Monday. They sat speechless as they learned that a $15 million budget shortfall had just become a surplus.

“We were able to capture and validate an additional $21 million, which dramatically changes the trajectory of how we were looking at the budget,” Thurmond said. If this is real money and not some accounting mix-up, it will be the first surplus in years.

Thurmond said he was pretty sure his find is real and that there are no hidden costs to undermine it, but he cautioned that he wanted to “re-re-validate” the numbers overnight before releasing his budget proposal for fiscal year 2014. The school board must approve the budget before the new fiscal year starts in July.

Board member Thad Mayfield struggled on Monday to understand what had to go wrong with the bookkeeping to produce such last-minute news, albeit good news. Why had they failed to notice the money before, he asked. Was it the result of a “process” error? Of human “oversight”?

“Both,” Thurmond answered. He said in a later interview with The Atlanta Journal-Constitution that the numbers “didn’t look right,” so he asked outside experts for guidance, and they suggested where to look.

People have ideas for spending the money.

David Schutten, president of the Organization of DeKalb Educators, said teachers have been living with furlough days — effectively pay cuts — for years, and those should be reduced. “This is incredible news,” he said.

Dawn Parker, a south DeKalb parent with a son at a charter school, said she would give teachers pay raises. “I think it is a big need,” she said. She figures the money was always there but went unnoticed because of “years of systemic hiding.”

Former school board member Nancy Jester, who also has kids in the district, was not ready to celebrate. She wondered if the new money resulted from creative bookkeeping. She noted that Thurmond’s predecessor, Cheryl Atkinson, confirmed last year that the district had routinely low-balled costs, thus painting a rosier budget picture than was merited and spending more money at the end.

“When you look at something that seems implausible,” Jester said, “it just might be.”

Last year, there was a similar last-minute announcement, but the news was all bad, as Atkinson revealed a steeper than expected drop in property tax proceeds. DeKalb went on to produce one of the harshest budgets in memory, cutting about $78 million to establish a $730 million budget for this year.

Thurmond had more good news on Monday: He said his staff also found $7 million in unaccounted for revenue in the current fiscal year, for a total upside of nearly $30 million. DeKalb still has money trouble: The district has to pay down about $15 million in deficit spending from a couple of years ago, but officials cut a deal with the state to make payments over four years for a negligible effect on each budget.