SACRAMENTO (CBS13) -- The city of Sacramento's Finance Department has learned it made close to a $3 million oversight on the police budget.

During its quarterly report the department told the City Council on Tuesday night that it didn't factor in enough costs for police overtime and holiday pay.

"It's more of a bookkeeping error than it is an expenditure projection," Police Chief Rick Braziel tells CBS13's Ron Jones. "It wasn't budgeted the right amount."

That means the Police Department will be forced to come up with ways to eliminate that $3 million oversight by next June.

However, the police union believes with issues such as Occupy Sacramento protests and other uncertainties, that could prove difficult.

"At this point we can't say that it will be corrected," said police union president Mark Tyndale. "We hope that it will … but if something big and unforeseen comes up, that could throw everything out of whack."

So could the Finance Department make such a huge mistake?

"I don't know if I want to call it a mistake," Tyndale says. "What it was is a budget miscalculation."

However, Braziel believes that through creative cost savings the $3 million oversight should be erased by next June.