In the UK (and presumably Australia) you can get an overdraft on your account and you don't get charged a fee. You get charged interest (like around 18%/year) c

In the UK (and presumably Australia) you can get an overdraft on your account and you don't get charged a fee. You get charged interest (like around 18%/year) charged only for the days. So it can be used as a buffer against charges, whilst you keep your money in a higher interest rate account.