With this feature you can enable Optix to create an invoice that is due today for additional charges from your users. We call this right-now-invoicing.
A user has a plan that gives them 10 hours of room bookings and they have gone over their allowance today by 2 hours. With this feature turned on, that user will receive an invoice that is due today for the additional 2 hours at the rooms standard rate (minus any plan discounts).
From your Optix web dashboard click Settings
Click Invoicing (you will need to have your payment gateway enabled to see these options)
From this screen you will see a drop-down section for 'Apply any additional charges' (see the screenshot below)
Select On a new invoice, due today
To fully realize the benefit of this feature it is advantageous to require users to enter a credit card when they sign up, you can enable this on the same Invoicing settings screen with the toggle next to 'Require users to add a payment method' (see the screenshot above).
Need more info on Invoices?