WESTFALL - Among more than 500 in the state, Delaware Valley has been one of only 38 school districts in Pennsylvania which does not use some type of income tax. But new state law requires that the voters be given a choice of property tax reduction methods, among them either a personal income tax or an earned income tax. The item must appear on the fall ballot. Before the ballot, the district must appoint an advisory commission to study district economics and demographics, business manager Bill Hessling said. While that study could be comprehensive in some districts, other economic and wealth indices, used by the state to rank and fund districts, will require a 1 percent tax level be put to Delaware Valley voters. Surveyed in 1997, district voters rejected any income tax. The board of education is not required to accept the commission recommendation, but the tax measure in some form, must appear on the ballot. While it might be expected that few voters would approve a new tax, school board members say an earned income tax would help shift the tax burden from property owners and retired people. Wage and salary earners and renters would pick up the difference. Even if the tax is defeated, other methods, including an increased income level for aged persons, property tax rebates, homestead exemptions and anticipated gambling revenues are in place to cut property taxes.