Montgomery County would be on the hook for up to $151 million in extra funding for its public schools under legislation circulating in the Maryland General Assembly.

Bills in the House and the Senate would allow counties to raise property taxes -- and in the House bill, income taxes -- above their current ceilings to help counties meet a state law that requires them to sustain or increase per-pupil funding each year.

Although the bills don't require counties to raise taxes, and local lawmakers have been vocal in their opposition, the proposals could force Montgomery County's hand if school funding escalates.

Under state law called "maintenance of effort," counties are required to sustain or increase how much they spend per student each year. But as economic times have toughened, Montgomery has failed to meet the funding floor for the last few years. Last year, the county took a $33 million penalty from the state -- to be incurred in fiscal 2013 -- rather than fork out the extra funding.

Montgomery County Public Schools is requesting $1.39 billion from the County Council, an increase of $22.2 million over last year and a sum that Council President Roger Berliner has committed to funding.

But under the bills, the county would have to seek a waiver for the current year -- essentially, a do-over of the budget. If Montgomery fails to receive a waiver, the county would have to fund the schools at the per-pupil level when it last met maintenance-of-effort three years ago, and would owe the schools $151 million instead of $22.2 million.

Even if the county does get a waiver, the county would have to give the schools $40 million under the House bill's provisions.

"To go back in time and call upon us to spend tens of millions of dollars more, or arguably $100 million-plus more, is really counterproductive," Berliner said Monday.

Shirley Brandman, president of school board, said in an emailed statement that the board supports legislation that "provides for a mandatory, but flexible, waiver process."

Last year, MCPS asked the Maryland State Board of Education for a "declaratory ruling" of the state's per-pupil funding requirement, which County Council members described as action toward a lawsuit over maintenance of effort.

The county increased school funding by $31 million last year, to $1.95 billion, less than the $82 million MCPS requested.