In Toast, a negative balance due is considered funds that are owed to the customer. This situation arises when item(s) the customer paid for are voided after the payment is processed. The solution is to adjust the payment.
In the example below, the customer's check of $59.52 has been paid by credit card.
After the payment is processed, the item "Harpoon" on the check was voided. Now the Balance Due changed from $0.00 to -$8.50 and the total changed from $59.92 to $51.42.
To correct the negative balance, select Pay to enter the payment screen. The following screen will appear:
If this item causing the negative balance was voided in error, select Edit Order and re-enter the identical item back to the check, then close the check.
If the voided item is correct, the payment must be adjusted so that the customer is not overcharged. Select Dismiss and proceed to the payment screen.
At the payment screen, again notice the Total Balance of $51.42 and the Balance Due -$8.50.
Select the customer's payment at the top of the screen (the line will turn blue) and the fields above the keypad will change. You now have fields for Amount Due, Tip and Total which can be adjusted.
The payment can be adjusted by changing the Amount field. You'll receive this notice about adjusting the amount from what was authorized when originally swiping/keying (Tap Adjust Amount to proceed):
Now, using the keypad, change the original total ($59.92) to the new total (51.42) so that the customer's credit card charge matches the check's total. Select Update.
Confirm the Negative Balance no longer appears and select Done to complete.