I have 28,500 in interest and taxes (15/13) and my taxes due dropped 1,100. Years previous that was 3k+, why the change? I see no explanation on Turbo Tax.

The difference between the Std Deduction and your deductions is lower this year since the Fed std deduction was raised..

Example IF you were married(no kids) and had 28,500 itemized deductions both years.   then in 2017 your Std deductions plus personal exemptions was ~$21,000 and putting in itemized showed a refund drop for the ~7,500 income drop.  But for 2018, the Std ded is 24,000 so the the itemized deduction change is only ~3500.

Then, too, your "taxes" deduction is capped  $10,000.  You can't get a  $13,000 deduction for state/local income taxes +Real estate taxes