Can I use workflows to update a field in an invoice which was paid for using a payment gateway?

Yes, you can. To do this:

• Go to Settings in the top right corner of the page.
• Click Workflow Rules under Automation.
• Click + New Workflow Rule.
• Enter the Workflow Rule Name.
• Select a Module for which you want to associate the workflow rule from the dropdown.
• Click Next.
• Select a Workflow Type.
• In the Filter the Triggers section, select the trigger as Edited, choose the criteria as ‘Payment Gateway’ is ‘PayPal’ (or any other payment gateway), and ‘Status’ is ‘Paid’.

Henceforth, when a payment gateway is associated to the invoice, and when the invoice is paid, this workflow will be executed. However, if an invoice has two payment gateways, say, PayPal and Authorize.net associated with it and if it is paid, the workflow will be executed even if it was paid for using Authorize.net. Also, when a payment is recorded manually for an invoice which is associated with PayPal, the workflow will be executed.

Please ensure that not more than one payment gateway is associated and the invoice is paid online for the workflow to be executed correctly.