The UK’s Competition and Markets Authority (CMA) has issued a warning to Monzo, NatWest Group, Virgin Money and Bank of Ireland after the banks breached a rule requiring them to send banking transaction histories to former account holders.

As a result of the Retail Banking Market Investigation Order 2017, banks and building societies are required to send customers a history of their current account banking activity within 40 days of a customer or small business closing a current account.

Transaction histories must be sent to at least 95% of such customers within 10 working days.

The CMA said it introduced this measure to make switching banks easier and to address concerns that customers who switched would lose access to their banking history – a key requirement for lenders offering credit.

In total, nearly 150,000 customers were not provided with their transaction history in the necessary timescale, with Monzo responsible for 143,000 of the cases.

Some transaction histories were provided a few weeks late, while others have been delayed by more than a year.

“The CMA has written to each of the four banks, which are sending all outstanding information to the affected customers,” said the CMA.

“If the banks breach the order again, the CMA can take further action by issuing legally binding ‘Directions’.

“These could include banks having to introduce specific training or carrying out annual compliance audits to prevent this from happening in the future.”

Adam Land, CMA Senior Director of Remedies Business and Financial Analysis, said: “Nearly 150,000 people were affected by these banks’ breaches, with the majority being former Monzo customers.

“This may have made things harder for people trying to borrow money or apply for a mortgage.

“The CMA’s work in the sector is making it easier for people to get a better deal from their bank.

“Banks must comply with all the rules – that includes providing a full transaction history promptly.

“We will be watching closely to make sure these leading names stick to their word and don’t let their customers down again.

“The Bank of Ireland, Monzo, Natwest Group, and Virgin Money should be in no doubt that the CMA stands ready to take further action if these failures are repeated.”

A spokesperson for Monzo said: “Since we identified the issue and reported it to the CMA in February 2021, we’ve fixed the problem and are telling affected customers that we can send them their transaction history if they’d like.

“This was an admin error, and we’ve also said sorry to the customers involved.

“Up until now, we’ve sent a full transaction history to any customer who has asked for it directly.”