This alternative is intended for quotes/customer orders that shall be handled with reversed liability for payment (reverse VAT). In some cases within the construction industry the buyer reports both the input and the output VAT. This can be selected by default on the customer in the Update Customer procedure. The reversed liability for payment will then be used by default during the order registration.
If you select the Reversed Liability for Payment box, the VAT code will be set to 4 (exempt from VAT). It is the buyer and not the seller that shall report the output VAT when it comes to sales of construction services.
If you use the setting Default customer group at reversed liability for payment, under Orders / Quotes under the Sales tab in the Settings procedure, the customer group for the reversed liability for VAT will be selected by default on the quote if you check the Reversed liability for payment box. The purpose is to code the sold goods/services correctly, based on the customer group.