Why will it not accept 0 for outstanding mortgage principle. I paid off the loan in Dec, hence no outstanding principle.

Enter the amount of your outstanding mortgage principal on January 1, 2019, if you're doing your 2019 income tax return(s).

Per IRS Form 1098-Mortgage, instructions for Box 2: 

• Shows the outstanding principal on the mortgage as of January 1, 2019.
• If the mortgage originated in 2019, shows the mortgage principal as of the date of origination.
• If the recipient/lender acquired the loan in 2019, shows the mortgage principal as of the date of acquisition.

I received 2 1098s as I refinanced in 2019.

It shows 0 in box 2/Outstanding Mortgage Principal of a of 1/1/2019 of the one they paid off. 

What do I put in TurboTax?

THANKS!!

Enter the amount you financed (the total amount of the loan) on the day you started the new refinanced loan. 

According to the IRS:

"Box 2. Outstanding Mortgage Principal Enter the amount of outstanding principal on the mortgage as of January 1, 2019. If you originated the mortgage in 2019, enter the mortgage principal as of the date of origination. If you acquired the mortgage in 2019, enter the outstanding mortgage principal as of the date of acquisition."

I am preparing my 2022 taxes.  My 2022 mortgage interest statement has an outstanding mortgage principal as of 1/1/22 of $0.00.  When I try to enter that amount in TurboTax, I am told that there must be a dollar amount not $0.00.  The loan was not generated till May, 2022.  What do I do?

Enter the amount you financed (the total amount of the loan) on the day you started the new loan in May.

@dlo3692