California policy-makers have a new study to help determine who bears the burden of the three most significant state taxes: personal income tax, sales and use tax, and residential property tax. By studying tax returns, as opposed to census figures, the research team led by Steve Sheffrin, professor of economics and director of the Center for State and Local Taxation at UC Davis, found that the income tax is the most progressive, the sales tax is regressive and the property tax is roughly proportional for annual incomes higher than $20,000. When measured by consumption, Sheffrin says the overall tax system is progressive. Lowest-income households, he says, pay a higher percentage -- as measured by consumption -- than do those earning up to $20,000 of income, but after that the effective tax rates rise sharply. Sheffrin and his colleagues published this work through the California Policy Seminar, which funded this study. It is a joint program of the University of California and state government that applies university research expertise to state policy concerns.