Earlier quoted context omitted.
That's funny, because on my federal tax return there's an entry where you deduct your state income tax. Sales tax, of course, is entirely different from income tax. http://www.irs.gov/publications/p17/ch22.html#en_US_publink1...
Something being deductible on federal is nowhere near the same as a tax credit. You don't get a tax credit for state/local taxes. You get a deduction (which doesn't apply under AMT). So, if you're in the 25% bracket, you can deduct your 10% state taxes, which reduces it from 25+10% to 25+10-(0.25*10). California's 9.3% is the top regular marginal income tax rate. There is also an 8-10% state/local sales tax. There is…
Call me a pedant if you like, but I'm just tired of seeing economic debates where people begin with best/worst case arguments, eg throwing out numbers which don't take inflation into account or suchlike. I felt the message I replied could have acknowledged that one number does not tell the whole story.