Northern Rock has launched two variable rate Isas.
Both its mini cash Isa and Tessa only Isa will pay an interest rate of 5.75 per cent.
The rates are guaranteed to be at least the equivalent of the Bank of England base rate until January 1, 2000. They will then adhere to the Cat standard limit of being no more than 2 per below base rates.
Both accounts have a minimum investment requirement of £1.