It's important with any business you come up with a revenue recognition strategy.
Use the "Invoices" tab in Firmhouse to export invoices, and use that as method to do revenue recognition and tax registration for your own bookkeeping.
What's important to note at this point is that a refund that is triggered will not automatically also generate a credit invoice for that payment. As such, whenever a payment is refunded, someone needs to make sure there's also a credit invoice generated for the refund.
To generate a credit invoice click the button in the upper right corner when viewing the original invoice you want to credit.
We recommend a scheduled bookkeeping moment, where you can check for refunds and generate any credit invoices at that moment.