“Washington state has the most regressive tax system in the country, according to a study by the Washington, D.C.-based Institute for Taxation and Economic Policy.

People earning less than $20,000 annually pay 17.3 percent of family income toward sales and excise taxes and property taxes, the report said. People making between $99,000 and $198,000 each year pay 7.6 percent toward their tax bill. Meanwhill, people in the top 1 percent of earners – those making more than $537,000 a year – pay just 2.9 percent, the report said.

“The lack of a progressive income tax to offset regressive sales and excise taxes, as well as property taxes, is the most important factor in making the Washington tax system so regressive. Taxes ought to be based on people’s ability to pay them, which means that the share of income paid in tax should rise as income grows, not fall sharply as is the case in Washington,” said Matthew Gardner, executive director of the Institute for Taxation and Economic Policy and the report’s lead author.”
(http://blog.seattlepi.com/seattlepolitics/2009/11/18/study-washington-state-has-usas-most-regressive-taxes/)