Bank of Ireland customers at 88 branches across the country are using their local services for the last time today.
Some of these services will now be offered at post offices instead but it marks the latest step in an accelerated shift away from over-the-counter banking towards digital and online services.
Bank of Ireland announced its planned closure of the 88 branches around the country in March as part of the downsizing of its network.
More than 920 post offices are offering local banking services such as cash withdrawals and lodgements six days a week. An Post has operated a similar partnership with AIB for more than 20 years.
The new partnership also comes as a major boost to an under-pressure post office network suffering the similar fate of local bank branches –declining footfall.
Both Bank of Ireland and An Post confirmed all preparations necessary to facilitate the transfer have been taken and the services are now in operation.
An Post said it had no concerns about the additional demands placed on its office network and it has pursued the partnership for a number of years.
“We have been chasing this Bank of Ireland partnership for many years and it is very important additional business for us," said Debbie Byrne, managing director of An Post Retail.
An Post said the addition of Bank of Ireland branch services in its network is "extremely positive" as it "further enhances An Post’s position as the trusted provider of community banking in every community".
Bank of Ireland said it was aware that widescale changes such as the branch network closure could cause concern but it has communicated with customers throughout the process.
"When changes to our branch network were announced in March, we made a commitment to our customers that no branch would close until services were operational at An Post locations. I can confirm that these services are now available in 923 An Post locations around the country," a Bank of Ireland spokesperson said.
"We know changes like this can cause concern for some customers. We have ensured that the An Post partnership is up and running before any branches close, and we have communicated fully with all our customers about every option available to them online, in a nearby BOI branch or at a local post office."
An Post has highlighted that many of the closing branches were not open on a full-time basis, unlike the post office network.
Addressing the challenges the changes pose to older customers, Bank of Ireland said 47% of their senior customers have registered for online banking, with almost two-thirds of those customers active in the last three months.
Bank of Ireland also said a dedicated support line remains available for carers and older customers to offer further support at 0818 200 398 or 01 250 0398.
The bank said it had taken this decision after a review of branch usage and footfall analysis as it works towards a sustainable and long-term banking system.
It has described the customer move to digital financial services and online banking as a "seismic shift" and as a result, it needs "to change how we offer our services to better reflect how people are banking today".
"It is clear that we’ve reached a tipping point between online and offline banking," the bank said.
169 local Bank of Ireland branches will remain open.