How do you account for interest paid to private investor?

[Kyle J.]

If I get a loan from a friend/family member/private investor, how do I account for the interest on the loan I pay to that investor? I know if I were borrowing from a bank they would issue me a 1099-INT form at the end of the year for tax purposes to show how much interest I paid and who I paid it to, but how does it work with private investors? I'm sure there must be someway to account for it, but I'm not sure what it is or what information is needed (i.e. do I need the person's social security or tax ID #). Thanks.