Some customers added a gratuity to their online payment, now they have a negative balance. How do I fix that properly?

Hey there, @jlitchfieldjr. 

Currently, QBO doesn't have the option to let a customer add a gratuity/tip when paying an invoice. 

If your customers pay your invoice more than its actual amount, it will automatically create a credit for them. This will show as a negative balance on their account.

However, you can still edit your invoice and create another line item to add their tip. This way, you can offset their balance. Let me show you how:

1. Open the invoice and click the second line item. Then, select Add new to create another service item for the tip.
2. Click Service and name it as Tip/Gratuity.
3. Create another income account to record the tip/gratuity. Just go to the Income account drop-down list and select Add new.
4. Choose Income in the Account Type drop-down list.
5. Select the income account under Detail Type and enter “Gratuity/Tips” in the Name field.
6. Click Save to save the information. Then, select Save and close to exit the Product/Service window.
7. Enter the gratuity amount in the second line item, then click Save and close. 
8. Once prompt, select Yes.

This will now remove the negative balance on your customer's account.

Additionally, there are several financial reports you can run to track your sales income in QuickBooks. They will show you helpful insights on the things you buy and sell, and the status of your inventory.

Don't hesitate to tag my name in the comment section below if you have further questions in managing your transactions. I'm always ready to help. Have a great weekend.