When you itemize your deductions, you have the option of claiming either state and local income taxes or state and local sales taxes, but you can’t claim both. You’ll want to use the option that gives you the greatest tax benefit.
Go to this section in Credit Karma Tax: Other Taxes Paid
State and Local Income Tax
Credit Karma Tax will automatically enter your state and local income taxes from your W-2 in the Other Taxes Paid section. It will be the line item titled State Taxes Paid (Calculated values appear from forms you’ve entered so far).
State and Local Sales Tax
If you saved your receipts throughout the year, you can add up the total amount of sales taxes you paid and claim that amount. If you do not keep track of your receipts, you can instead use the optional sales tax table for items other than big ticket purchases like vehicles, boats, or home renovations.
You can enter this amount in the Other Taxes Paid section of Credit Karma Tax under General Sales Taxes.
As a result of the Tax Cuts and Jobs Act of 2017 (2017 tax reform): taxpayers who itemize may only deduct their state and local property and income (or sales) taxes up to a limit of $10,000 in total for individuals. You may not be able to deduct as much as you were able to in previous years if you live in a state with high income, property, and sales taxes.
Source: irs.gov