How NetSuite Billing Schedules Interact with Discounts on Sales Orders?

When a discount is applied at either the header or line level, and the billing schedule is configured at the sales order header, NetSuite will divide the total net amount of the order across the intervals defined in the billing schedule.If a billing schedule is available and applied at the line level, the discount is typically tied to the items preceding the discount item (or all lines above the subtotal before the discount). The discount is then calculated for the applicable items based on the billing schedule assigned to those specific items. This behavior remains consistent regardless of whether the Discount Item is defined as a non-posting or posting type.For scenarios where discounts are not intended to be tied to specific items, and if revenue recognition and non-posting discounts are not in use, a previous approach involved assigning a negative rate and a billing schedule to a non-discount item at the line level. While this method might appear to calculate a negative amount when using 'Next Bill' functionality, it is generally not aligned with current NetSuite best practices and may lead to undesirable outcomes or errors, such as generating credit memos instead of direct negative invoice lines, or errors if the total becomes negative. Additionally, the total amount of an invoice cannot be less than zero.