What is the voucher payment method field in tax settings

What is the voucher payment method field in in tax settings? 

Why can't I leave the voucher payment method field blank? 

Error Message: A voucher payment method is required

• Enterprise ERP
• Payment Entry
• TN Tax
• Voucher Payment Method
• Tax Relief Voucher
• 2021.8+

The voucher payment method field was added to tax settings as part of an enhancement to allow TN tax sites the ability to have citizen pay using tax vouchers through the tax relief program. Currently the program requires a payment method to be selected in order to accept any changes in the tax settings program. Support recommends adding in a place holder payment method to be used in this drop down. If an existing payment method is selected without the proper setup, the system will block payments using the selected payment method. 

How to Add Additional Payment Methods