You need to focus not on the payment, but first on the rate, then on the resulting payment. You'll go back to the date of active duty abd pick up from there forward at a rate no greater than 6%. If you were charging less, that is fine.
Being charged off is an internal status. It's a bank classification and bookkeeping entry with the exception that your post maturity rate could be less than 6%. I doubt that, but I don't know the rules in all the states. If the borrower came to you and said "I want to make this right, what do I owe" your response wouldn't be that it was charged off and the debt is zero. So put that aside and do the computations to ensure you don't attempt to collect more than allowed, or report it to the IRS as a larger amount than is owed if you 1099-C it.
My opinions are not necessarily my employers.
Rules and Regs minus Relationships equals Resentment and Rebellion. John Maxwell