All monthly variable interest rates move in line with the Bank of England's Bank Rate (calculated on monthly basis) and can only change at the start of a new billing period. They are calculated by taking the Bank of England's Bank Rate at the start of the billing period and deriving a monthly bank rate which is added to the monthly cash/card business rate. Monthly variable rates start at 1.21%. We will not pass on negative bank rates. To see the latest Bank of England Bank Rate, check their website.