In order to open the account, savers will need to be an existing member (either by having a Nationwide savings, mortgage or current account) by 16 March.

The ‘member exclusive’ FRISA pays a market-leading rate of 0.75%. Savers will be able to open the account (with a minimum of £1) in branch, online or using Nationwide’s banking app.

How to get the £50 cash

The member exclusive FRISA will accept transfers-in. Nationwide members who use the ISA transfer service to move at least £10,000 from another ISA, will receive £50 cashback.

To benefit from the offer, ISA transfer-in applications need to be submitted while the account remains on sale.

The cash will be paid into a Nationwide current account or savings account.

Tom Riley, Nationwide’s director of banking and savings, said: “As a mutual, we continue to look at how best to reward and offer value to our members and the launch of our new Member Exclusive FRISA does just that.

“As we fast approach the end of the tax-year, this new account means our current best on-sale ISA rate is available exclusively to existing members. We want to ensure that this new account is available to as many members as possible, which is why it is available to open online and via our branches. New members will still be able to benefit from our highly competitive Triple Access Online ISA.

“In what remains an ultra-low interest rate environment, we have tried to find alternative ways to reward all types of savers, which is why we are launching our first ever ISA transfer incentive, exclusively for existing members.”