How can I make sure there is proof I loaned someone money?
You do want a promissory note, but a promissory note is just a written contract, signed by the borrower, wherein the borrower promises to pay the lender a particular amount at a particular future time. A promissory note providing for multiple payments can include an “acceleration clause” that causes the entire outstanding principal to become immediately payable if the borrower defaults on a payment. This can be useful, since the lender probably doesn’t want to sue the borrower ever month or so as the payments individually become past due. I don’t know if Wisconsin imputes an acceleration clause in all promissory notes, but if you want the behavior I described, you might as well include it explicitly. If you do include an acceleration clause, consider whether the borrower should be allowed to “cure” a breach before the entire amount becomes due. If you were planning on there only being a single payment at maturity, this is all pretty irrelevant. More generally, make sure your promissory
