Martin has agreed to pay his father interest on the $2,500 loan to help get the business started. The last payment was made on 12/31/21. The annual interest rate (simple interest) on the loan is 6%. You forgot to pay him in January. You call and let him know that the check will come in February. TIP: Just because you didn't pay it in January doesn't mean you don't owe it in January. Consider whether you need a new account here