Fixed Rate ISA SaverChoose to save over 1-4 years, with the peace of mind that you'll have a guaranteed rate of interest. Minimum opening balance - £500 Maximum balance - up to £5,100 in any one tax year. No withdrawals, No additional deposits - after account opening. Manage your savings - In branch, by phone or view your balance online 24/7. You can only fund one cash ISA during any one tax year. If you already have an ISA with another provider and want to take advantage of our cash ISA interest rate, ask to transfer your ISA today.