I found the following note on the Chartered Accountants Ireland website dated 27 January 2014
"Members are advised that ROS direct debit payments to Revenue are taking up to 7 working days to clear. We have confirmed with the Collector General’s office that under the SEPA arrangements, ROS direct debit payments made for the first time under these arrangements are taking up to 7 working days to be debited from a taxpayer’s bank account. Therefore this means that while a ROS direct debit payment may have been made on or before the relevant due date and payment confirmation has been received from Revenue, the monies are not taken from the relevant bank account until a week later. Under the SEPA arrangements, subsequent ROS direct debit payments are expected to take up to 4 working days to clear."