Since you are requiring the payment of accrued interest PLUS the principal reduction, I would say $9,840 is the balance at the end of month 61.
I always used to list the principal balance as of year-end, so I would disclose the month 72 principal balance. If I did my calculations correctly, that would be 8,374.25 in your example.
For payment, I would always disclose the highest payment in the year, so that woule be the month 61 payment.
[This message has been edited by pbrinker (edited 02-14-2002).]