TSB Bank has been fined £48.65m by the Financial Conduct Authority (FCA) and the Prudential Regulation Authority (PRA) for failures related to IT migration.

In April 2018, TSB updated its IT systems and “the platform immediately experienced technical failures”, which “resulted in significant disruption” to the bank’s services including branch, telephone, online and mobile banking, the regulators said.

All of TSB’s branches and a sizable number of its 5.2 million clients were impacted by the outage.

The authorities’ inquiry revealed that TSB had inadequately planned and managed the IT migration project.

The lender also was unable to manage the operational risks brought on by its agreements with its crucial third-party provider for IT outsourcing, they said.

FCA executive director of enforcement and market oversight Mark Steward said: “The failings in this case were widespread and serious which had a real impact on the day-to-day lives of a significant proportion of TSB’s customers, including those who were vulnerable.

“The firm failed to plan for the IT migration properly, the governance of the project was insufficiently robust and the firm failed to take reasonable care to organise and control its affairs responsibly and effectively, with adequate risk management systems.”

TSB could not resume normal operations till December 2018 and it has provided £32.7m in compensation to the affected customers.

The FCA and PRA granted TSB a 30% discount on the total fine issued since it promised to rectify this issue otherwise the overall financial penalty would have been £69.5m.

TSB CEO Robin Bulloch said: “We would like to apologise again to TSB customers who were impacted by issues following the technology migration in 2018. We worked hard to put things right for customers then and have since transformed our business.”

Earlier this month, the FCA imposed a fine of £107.79m on Santander UK for repeated failure in its anti-money laundering (AML) controls.