Definitely have a lawyer help you. What you want to do is in essence give her a private mortage that is, the money you loan her to pay off her bank mortgage will be secured by her house--that's the only way to make sure your investment is protected.  If you are not paid, you could foreclose on the home or be paid from the proceeds of any sale of it. You will want an attorney to help draw up the loan instrument and mortgage, and make sure they are properly recorded, so they are enforceable. Yes, she can also make a will leaving you something, but that doesn't help as much as you may think, since a will may be changed at will therefore, if, say, the two of you break up and she decides she doesn't care if you are ever repaid, she could cancel or change her will and deprive you of that protection.