This is a broad question, so these answers are broad too, pertaining to Federal
Since you are new to TT, go to forms and click through each form and get acquainted with the data and worksheets. Compare to your documents from the previous year. For instance, review the tax documentation from your tax accountant from the previous year to make sure you are not missing any potential deductions from carryovers.
If you didn't file for an extension, you will have a penalty to pay.
Starting in 2018, mortgage interest was capped at 10K, so anything in excess of 10K is not deductible.
If one of your children is above 17 than the child tax credit doesn't apply and instead you may have only a $500 credit toward other dependent until age 19 (I think).
Itemize your medical expenses to see if they qualify for a deduction.
Check to see if the Standard deduction was applied instead of itemized deduction.
Good luck!
