Sending the invoice to KSeF Open the Invoices, Debit and Credit Memos form. Click the invoice number that must be sent to KSeF. The invoice is displayed. Select the Send to KSeF check box. Note: This check box is selected by default, if the invoice category is marked as KSeF for the customer. Click the Invoice Posting option. The Invoice Posting form is displayed. Click Process. Note: You can verify the status of the invoice sent to KSeF on the KSeF Documents form.