Pupil-teacher ratios in Lafayette Parish public schools might increase by one, two or three students per classroom as the school system grapples with another year of budget shortfalls.

The estimated shortfall for 2015-16 ranges between $18.1 million and $22.5 million — depending upon whether the School Board plans to recognize projections for increased tax revenues next year, said chief financial officer Billy Guidry.

The board’s finance committee meets at 6:30 p.m. Wednesday, when Guidry will share information about the shortfall and the committee may tackle the issue of increasing student-teacher ratios.

Such an increase could save from $4.2 million to $9 million a year, Guidry said Monday.

The ratio changes were first on the board’s agenda in February and it’s possible the full board could make a decision on any changes at its next meeting on March 18, Guidry said.

Last week, Guidry told the committee the shortfall could be as high as $22.5 million, though Monday he added that if board members recognize projected increases in property and sales tax revenues, the starting number for the shortfall drops to $18.1 million.

“These are very preliminary numbers and we need to get a feel for what the board is going to be in favor of,” Guidry said.

A list of more than 30 suggestions for balancing the budget will be presented to the board. In addition to the student-teacher ratio, other suggestions include: eliminating the annual salary increase for employees, for an estimated $2 million savings; using $3 million from the rainy day fund; shifting $1.5 million in teacher positions from the general fund to a 2002 sales tax fund; and eliminating some positions.

He said several factors led to this year’s shortfall, including a reduction of about $6.9 million in state per pupil funding because those funds followed the students who decided to enroll in charter schools; rising insurance costs; and $13.7 million in one-time funds that were used to offset last year’s shortfall.

Last year’s budget process started at a more than $20 million shortfall and led to a budget process of more than 20 workshops and meetings. The board in place at that time routinely rejected or failed to consider balanced budget proposals from then-superintendent Pat Cooper, who filed a lawsuit challenging the board’s budget approval process. Cooper’s claims weren’t supported by a state district judge. As part of his challenge of the board’s decision to approve cuts that weren’t in line with staff recommendations, Cooper refused to implement the board’s approved budget and continued operations using the 2013-14 budget.

The budget wasn’t implemented until November, following Cooper’s termination. The board’s approved budget didn’t contain some positions, requiring it to approve two budget revisions totaling about $6.2 million in December to prevent layoffs and administrative and teacher transfers to ensure continuity on campuses.

Guidry said the next round of budget workshops will start next month.

Follow Marsha Sills on Twitter, @Marsha_Sills.