Turbo Tax is asking for the debt on date last secured. What is this or where do I find it?

Because of new tax laws concerning mortgage interest, the program is asking i order to establish if all the interest is deductible. 

If you took a loan out for 200,000 to purchase a home, but now the loan balance is 300,000 because you took a line of credit out on the original loan, that interest may not be deductible.

Enter the amount of the loan when you last secured it means, what was the loan amount the last time you signed loan documents for it. 

If you borrowed 200,000 for a home and never took cash out, enter 200,000. 

If you refinanced for 300,000, enter 300,000 as that amount.