The year ending balance for your mortgage (balance as of Jan. 1, 2019) is not going to be listed on your 1098 form. You will have to find the balance either on a mortgage statement or by contacting your mortgage lender.
This information is needed due to the changes in the amount of mortgage interest that can be deducted beginning in tax year 2018. If your mortgage is refinanced or more than $750,000, then the ending balance is needed to determine the amount of interest that can be included as a deduction in 2018.
Here is more information on how the 2018 Tax Reform changes can affect your tax return. Click on the blue arrow for Mortgage Interest and Home Equity Loans:
https://ttlc.intuit.com/replies/6971774
