The mutual picked up 146,676 customers between October and December 2022, the biggest number by far compared to any other bank or building society.

Even after factoring in the number of customers who left (34,735), Nationwide had a net gain of 111,941 customers.

This is the highest since the Current Account Switch Service (CASS) launched, according to Andrew Hagger of Moneycomms.

He added that it also dwarfs the previous highest quarterly net gain of 66,145 by Santander in Q2 2015.

The boon to Nationwide numbers appears to tie in with the building society launching its £200 switch offer back in October, a big boost to the previous £125 cash incentive for new customers.

Hagger said: “The Nationwide performance was no doubt mainly driven by its £200 switching incentive which was launched on 3 October 2022. This was also a period where the cost-of-living crisis was starting to hurt consumer finances, so a £200 freebie probably seemed more appealing than ever.”

Pay.UK which owns and operates CASS revealed that in second place, based on net gains, was NatWest with 5,616. It saw 37,421 customers come on board, however 31,775 voted with their feet.

In third place came challenger Starling Bank with a net gain of 1,810 customers. It saw 10,476 savers join in the three-month period, however 8,666 left.

At the other end of the scale, Santander recorded a net loss of 35,046 customers. During Q4 2022, 12,951 people opened a current account, but 47,997 switched away. Barclays (-22,945) and Halifax (-20,287) came in second and third place respectively in terms of customer losses.

Nine million switch milestone

While the customer switch data is three months in arrears due to “commercial sensitivity”, Pay.UK releases total but anonymised figures on the number of recent switches.

In the first three months of 2023, a total of 341,075 switches were made – the highest total ever – and over 70% higher than the same period last year (196,964).

Pay.UK said its data points to switchers preferring their new current account to their previous one, with service-related, non-financial benefits “continuing to be the main reasons end users preferred their new account”.

Two in five cited online or mobile app banking as the reason behind a move, while a quarter said they wanted to switch because of the spending benefits available at a new provider.

Over the year (1 April 2022 to 31 March 2023), there were 1.13 million switches across the 48 participating brands.

Since the launch of CASS which is approaching its tenth anniversary, 9.1 million switches have taken place, with 134.4 million payments having been successfully redirected.

Euan Ballantyne, head of product at Pay.UK, said: “It is encouraging to see Q1 2023 switching figures surpass Q1 2022’s figures by over 70%, demonstrating the continued relevance of the Service to consumers and businesses across the UK.

“Those considering a new current account, for whatever reason, can be assured that the Current Account Switch Service, with its nine million switches and 134.4 million successfully-redirected payments, is a quick, free and easy process.”

What is the Current Account Switch Service?

CASS is free to use and allows customers to switch current account between participating bank and building societies, with all direct debits and standing orders brought across automatically. All payments that usually come into your account, such as salary will also be moved.

The switch will be completed in seven working days, with customers able to choose and agree a switch date with their new current account provider.

If anything goes wrong, the CASS guarantee means that customers will receive a refund of interest and charges on their old and new accounts.

Meanwhile payments accidentally made to or requested from old accounts will be automatically redirect to the new account.

You can switch if you are using your overdraft, but you will need to agree an overdraft facility with the new firm.