There is no 1099 because going more into debt is not tax reportable. It isn't taxable income to you. It's more Debt you will need to pay. That's liability; not income. It is cash flow. Don't get all of that confused.

But the borrowing on the home (if not for a qualified purpose) means understanding the mortgage interest write off rules. Since you are supposed to be doing taxes for your client, and not getting personal tax advice, you will want to learn what applies. Start here:

https://www.irs.gov/publications/p936

And there is never a reason to ask the same group of people the same question more than once. That's no way to treat peer users.