The Competition and Consumer Protection Commission (CCPC) has said Ulster Bank and KBC current account customers need to take action and switch banks to avoid being left without banking services.
Ulster Bank and KBC will cease transactions in the Irish market next year.
The CCPC said customers should take action sooner rather than later and its research shows that fewer than half of customers who need to open a new account have done so.
The research shows 81% of those customers plan to do so, but only 44% have opened new accounts so far.
Around 20% of customers said they have not done anything about switching current accounts yet.
Customers who have started or completed the switching process identified transferring direct debits as the biggest challenge, followed by a lack of alternatives, difficulties accessing in-person support, the requirement for too many forms and documents and too much time and hassle.
It also found 29% of respondents would consider an online-only banking provider.
The CCPC has developed a step-by-step guide to completing the transfer of direct debits and has also published information on switching current accounts on its website.
Ulster Bank officials told the Oireachtas Committee on Finance in May they intend to cease transactions in the Irish market in March 2023, while KBC officials said transactions will cease in August next year.
The research for the CCPC was carried out by Ipsos MRBI between 13 June and 22 June across a nationally representative sample of 201 existing or former current account customers of Ulster Bank or KBC.
Bank customers urged to take action now
Speaking on RTÉ's Morning Ireland, Director of Communications with the CCPC Grainne Griffin said a guide has been published online to assist consumers in switching banks with a comparison tool for different types of bank accounts.
Ms Griffin said Ulster Bank and KBC have strong obligations to help people move their accounts. They must have a "switching" or transfer pack for customers.
"It means that the bank will then take the first step in transferring direct debits. They'll send out their new details to their various companies that they're signed up with, but it doesn't cover everything, and I suppose if consumers have reoccurring payments on their cards, which is really, really common, they'll still need to do that side of it themselves."
She said customers do have deadlines set by the banks, but she urged people to change banks before those deadlines as the process takes time.
"It's really not the deadline that you want to focus on. It's really important to take action now.
"This process is something that will take months rather than weeks, so it's something that you want to start early, and you want to try and avoid being caught up in any delays."