Just to clarify, all I/O loans give you the option to pay principal. I pay about $1200 of additional principal each month which is actually more than what the 30 year amortized payment would be. As far as I know there is no way to tell what the actual loan balance on individual loans are until they get paid off. I assume this because I get solicitations almost daily and they assume my loan balance is the original loan amount which it is not.
