While we usually support school-funding measures, two Contra Costa districts are asking too much as they seek voter approval to raise property taxes.

We urge rejection of Moraga's Measure A in vote-by-mail balloting due back by May 8, and West Contra Costa's Measure K on the June 5 ballot. Each requires two-thirds approval for passage.

We understand districts are struggling to balance budgets. But these measures create unreasonable burdens on property owners.

In addition to the base tax of 1 percent of assessed value, property owners pay school taxes for two purposes: to retire bonds that fund construction and to contribute to ongoing education costs through what are called parcel taxes.

Both upcoming measures would raise existing parcel taxes. We examined how that would affect property owners' total education tax burden.

  • Moraga: Because children only attend Moraga schools for K-8 education and then go to the larger Acalanes district for high school, property owners pay taxes for two school districts.

    Measure A asks district voters to permanently increase parcel taxes for K-8 by $225 a year. It follows voter approval of two Acalanes parcel taxes in the past two years. Consequently, the two districts already charge $626 per year for ongoing expenses.

    In addition, property owners pay about $70 a year for every $100,000 of assessed value to cover payments on school bonds.

    Adding it up, the owner of a home with an average assessed value of $575,940 currently pays $1,029 in extra property taxes for education. That would increase to $1,254 under Measure A.

  • West Contra Costa: This district has gone to the tax well too many times.

    District leaders brag that their massive school construction program enjoys widespread voter support. But for each of five bond measures put to voters, the ballot analysis referred only to the immediate proposal, hiding previously approved costs.

    The district also underestimated the tax rate needed to pay off the bonds. Property owners soon will pay about $250 a year for every $100,000 of assessed value, one of the highest school bond tax rates in the state.

    Meanwhile, the district collects two parcel taxes for ongoing expenditures. One is a flat $72 per parcel, the other 7.2 cents per square foot.

    In 2010, the district unsuccessfully sought to double the 7.2-cent rate. In 2011, the district and Richmond officials asked voters in that city for a hefty sales tax increase, with half the money going to education. Voters rejected that.

    Now Measure K asks district voters to increase the 7.2-cent rate on the second parcel tax to 10.2 cents and extend the sunset date from 2014 to 2017.

    For the owner of a district-average 1,367-square-foot home with an assessed value of $215,125, total annual school taxes would increase from $708 to $749. The bill would be more for larger homes and those with greater assessed value.

    That's not fair to property owners in some of the Bay Area's poorest communities.