I took a loan for 20k on 11-1-2007, my payments are 386.56, but I'm paying 400.00 every month. When is going to be my last payment, or what is the formula to find out when is going to be my last payment?
Just plug "loan calculator" into a google search and it'll bring up many loan calculators for your area, Rogelio. Then you just put the appropriate info into the calculator and it'll give you your answer.
To piggy-back on JTT's post, you'll need the principal amount of loan, your interest rate, and term of the loan (number of months). Plug in your payment amount, and presto!
He will also need to know how the loan agreement treats excess payments. On most home mortgages, it goes direct to principle. That is not necessairly the case here. We probably shouldn't make the assumption that that is a universal convention, and that might make the online calculator kind of approximate.