Currently, there is no way for a user to pay for an invoice before its due date. However, there are two ways that you can allow your users to settle their payment before their invoice's official due date.
Option 1: Within Optix, create an upfront, one-time invoice for the amount on their upcoming invoice, then zero out the charge from the 'upcoming invoice.'
- Create an upfront, one-time invoice for your user within Optix which matches the charges outlined in their upcoming invoice. Mark this new invoice as due today
- Modify their upcoming invoice, using the 'discount' section to offer a full discount to nullify the charges listed
Option 2: Outside of Optix, charge them manually for the amount listed on the 'upcoming invoice,' then mark the corresponding Optix invoice as 'paid' on the day that this invoice becomes officially 'due.'
- Charge the user for the amount listed on their Optix invoice (i.e. a manual charge via your payment gateway account)
- Let the user know that their payment has been processed
Note: The user may still receive a reminder through Optix that they have an invoice due, since you won't be able to mark the invoice as 'paid' within Optix until the invoice reaches its due date. Make sure and prepare the user for this and ask them to ignore such reminders.
- On or after the invoice's due date, go into the users account to manually mark the invoice as 'paid'
Note: If the user is on auto-payments, you'll need to mark the invoice as 'paid' as soon as the due date arrives, otherwise you risk of the client being double-charged.