It took me ages to find a way to import ALL California tax rates into WooCommerce. I started by hand, and after a while I said to myself “California is crazy! I wouldn’t want to be an accountant there!”.
As usual, I looked for existing free and premium plugins, but I decided to do it my way. this tutorial gives you a ready-made CSV with all California US tax rates (as of 9 August 2014). Yes, it’s out of date, but you can download it, see how it is built, revise it with the correct rates, and follow the tutorial. Continue reading WooCommerce: Import California Tax Rates (.csv)