I live in a high-tax state. Last year my SALT deduction was about $15K, which I assume was the amount that my spouse & I paid in "State income taxes" (W-2 line 17) plus property taxes paid -- correct?
I also know that the new tax rule caps SALT deduction at $10K.
So I am trying to figure out why even though this year we spent almost $13K in State Income Taxes + property taxes, why TurboTax is showing SALT tax total of about $8K and not an even $10K (the cap).
There are a few things that contribute to the State and Local Taxes limitation of $10k: like you mentioned the state income taxes from your W-2, and your property taxes are included. Also included are any local taxes from your W-2, some state disability payments (like California SDI), any estimates you paid to your state or city, any payments you made in 2018 to your state for a 2017 balance due, and your personal property taxes like your DMV fees.
For your question about only $8k showing, it depends where you might be looking in TurboTax as to what is being included. I would recommend reviewing the actual tax return before filing, and looking at Schedule A, line 5e to confirm that your deduction is being calculated as the full $10k.