Why do we need to use the Vendor date for any posting date? Except for calculating the due date, I don't think we have to post it on GL, IC or AP as the goods are not received yet. You still could do an advance payment if necessary. If a vendor takes 2 months to send the invoice and the year is already closed, the invoice is just an accrual and it will be posted in the next year. Therefore, the vendor document date is not important for posting the transaction and should not be used.