has launched a competitive fixed Cash with a 4.25% interest rate, along with the chance to claim a free £50 e-voucher. The interest rate is fixed for one year, and savers can launch the account with a minimum deposit of £500.

Fixed-rate Cash ISAs have gained popularity in the current high-interest rate environment, offering people living in the UK a way to save without paying tax on the interest earned, up to an annual limit of £20,000 for the 2025/26 tax year. Following the Bank of England's last Base Rate cut to 4.5%, savings interest rates have been on the decline. This makes fixed-rate accounts more attractive, as they lock in the interest for a set term, allowing savers to secure higher returns for longer.

Savers must be aged 18 or over to open the Santander account, and interest is paid once a year and at the end of the term.

The term starts on June 1, and deposits into the account can be made up to and including June 30, 2025. You can withdraw money, but you'll have to close the account, and a charge equivalent to 120 days' interest will be applied.

To get the £50 e-voucher, savers must transfer their full balance, a minimum of £10,000, from a non-Santander ISA.

But while Santander may be offering a competitive deal in the one-year fixed rate sector, it isn't quite topping the table. Punjab National Bank takes the lead with an Annual Equivalent Rate (AER) of 4.35%.

Savers aged 16 and over can launch the account with a minimum of £1,000, and interest is paid on maturity. Earlier access is permitted on closure only, subject to providing 30 days' notice, and no interest will be paid.

Castle Trust Bank falls just behind with an AER of 4.26%. Savers can also need a minimum deposit of £1,000 to launch the account, and interest is paid on maturity. Earlier access is permitted on closure only, and will be subject to 90 days' loss of interest.

For savers with smaller sums to invest, OakNorth Bank also offers an AER of 4.26% on a minimum deposit of £1. Interest is paid monthly, and earlier access will be subject to a 90-day loss of interest.

Despite the higher interest rates on offer, millions of savers are thought to be missing out on the top rates. New research from Spring, a savings app owned by Paragon Bank, estimates that Britons are losing £20billion in interest every year, as a staggering £526billion sits idle in current and low-interest savings accounts.

Rachel Springall, finance expert at , said: "There are unfortunately some savers keeping their hard-earned cash in a current or savings account that pays poor returns and is eaten away by inflation. However, this money could work so much harder if consumers just take a little time out of their day to open an easy access account that pays better returns, which is quick and easy to do."