PTSB said it has resolved a technical issue for the majority of its customers who have been experiencing delays in sending and receiving payments.
The bank is also having problems with its app.
People have been expressing their frustration on social media over the technical issues.
The last Friday of the month is pay day for many workers and pensioners, and today is also Black Friday, one of the busiest shopping days of the year.
In a statement, PTSB said that due to a technical issue with a third-party payments provider, some customers may have experienced delays when sending or receiving SEPA payments.
SEPA stands for Single Euro Payments Area and is the system for processing euro payments across the EU.
"PTSB has resolved the payments issues reported this morning for the majority of customers," the bank said.
"We are continuing to work to resolve this issue for any remaining customers as a priority."
"A number of banks in countries in Europe were similarly impacted," PTSB said.
It added that customers will not experience any financial detriment as a result of the issue.
The bank said that for any customers experiencing difficulties with its app, they can log on to the desktop website.
"We are working on resolving app access issues for these customers as soon as possible and apologise for any inconvenience caused," PTSB said.
The bank said it is investigating if the payment delays and app issues are linked.
