The IRS can take 24-48 hours to process a return, sometimes longer if the volume is heavy. Therefore, if you send your return and set the payment date for the same day, the IRS may not have processed your return before the end of the day, and when they process your return, the date has passed and they often will not take the payment.
It is suggested that you file your return at least two days before you want the payment to be taken, to ensure this does not happen again.
