More than 20,000 social welfare payments due to have been made to customer's bank accounts today will not be made until tomorrow.
The Department of Social Protection says the delay will not affect customers of Bank of Ireland or Allied Irish Banks who received their payments this afternoon.
But a department spokesperson said that 20,600 others are affected.
Ulster Bank is helping 9,000 of them through its emergency cash access service which can be accessed by visiting a branch with a valid ID or by phoning 1850 424 365.
The department says where possible Permanent TSB branch staff will try to facilitate customers who have concerns.
But it adds that "customers of all other banks will receive their payment in their accounts tomorrow".
It advises any customer experiencing difficulties as a result of the delay to contact their local Department of Social Protection community welfare service for assistance.
It also apologised for the inconvenience caused.