Whenever one of your customers is enrolled in a payment plan, the outstanding balance for the entire order is divided evenly between all installments whose payment date is after the current date.

For example, if one of your customers registers for a session that costs $500, and they pay a $200 deposit at the time of registration, with the remaining balance distributed over three installments, then provided that all installment dates are in the future, then each payment will be for $100.

If however, one of the installment dates has already passed, then the balance will be split between the two installments, so that each payment will be for $150.

This works the same way regardless of whether a registration is entered through your online registration form or internally through front desk registration, and also when a payment plan is cancelled and re-applied, perhaps because of a transfer, The same logic also holds for transfers, and when you put one of your customers on a payment plan after the time of registration.