Check for data entry errors, especially commas and decimals.
Did you have some special deduction in 2017, such as a one time medical expense? Also be aware that, for 2018, state/local/property/sales taxes are capped at $10,000. Also see:
https://www.cbsnews.com/news/9-tax-deductions-individuals-can-no-longer-claim-for-their-2018-taxes/
