Herk, you can close on that one, but not quite right on. You get to add to your sales tax deduction any sales tax on major purchases. The sales tax on cars, boats, RV's, and even home improvement or new home construction is considered to be major purchases. You then add the major purchase sales tax to the sales tax from the sales tax table for your income and your state/county/city and if that amount (major purchase sales tax plus the amount from the table) is greater than the amount of state income tax you paid, then you can take the sales tax deduction rather than the state income tax deduction. I have some clients that even keep track of the actual sales tax they pay and use that. Usually it is substantially more than what the sales tax tables give you.
I hope that helps to clear this up. If this sounds confusing, it is just the way the tax law is written.
2011 Berkshire 390bh