When an invoice is entered with an invoice date in the open project accounting and closed accounting periods, the accounting date is the same as the original invoice date, but the project accounting date is the first day of the first open project accounting period. This ensures that the invoice is accounted in the correct accounting period and recognized in the correct project accounting period. https://docs.oracle.com/en/cloud/saas/project-portfolio-management/20c/oapfm/manage-project-invoices.html#OAPFM2355911