If you are using SEPA Direct Debits as your payment method (and/or iDeal in The Netherlands), the Payment date is the date at which the SEPA Direct Debit payment has been triggered (or the moment of the iDeal transaction).
It can take a couple of days before the SEPA network returns the payment status of a SEPA payment to the Firmhouse platform. This way, the date of a SEPA payment is when the SEPA debit was initiated, not necessarily when it was successfully paid.
The invoice date is triggered at the moment an invoice is generated.
For SEPA payments, the invoice date is the moment that the payment is imported by our platform from the Payment Service Provider.
For successful iDeal payments, an invoice is generated immediately.