The account balance is not payable. It is meant to show you the running balance of total payments and total charges at any point in the season. Ideally, by the end of the budget season, total payments for that period will be about the same as total actual charges, with the difference being reflected in the account balance. In contrast, amount due reflects items not covered in the budget plan, which is usually zero. The amount due is payable, except for leases as noted above.