There is no personal income tax in Washington. State sales taxes are 6.5% and may jump to 9.5% depending on the locality. There is an estate tax with a $2 million exemption amount.
There is technically no corporate income tax in Washington. However, it has a Business and Occupation tax which essentially is an income tax based on gross receipts rather than net. Tax rates can be found at: http://dor.wa.gov/Content/FindTaxesAndRates/BAndOTax/BandOrates.aspx