Taxes apparently will not go up in the Mars Area School District next year.

The school board yesterday approved a $37.20 million tentative budget that holds the line on taxes.

Millage, however, will decrease from 132 mills to 99 mills because Butler County changed its assessment system, said Josh Schwoebel, district spokesman.

Previously, the county assessed properties at 75 percent of their 1969 value. This year, the county will assess at 100 percent of the property's value in 1969, the year of the last countywide reassessment. Ninety-nine mills are expected to bring in the same revenue under the new system as 132 mills did under the old one.

The district expects to bring in $35,125,000 in revenue next year and will spend $37,201,640. The remainder will be taken from the fund balance, leaving a surplus of $2.07 million, Mr. Schwoebel said.

The preliminary budget passed 8-0 with Gordon Marburger absent. It will be available for review by the public at the district administration building and will be voted on at the board's June 9 meeting.