I suppose the trustees of an SMSF cannot decide to invest in a mortgage offset account for the mortgage % rate as return (e.g. 4.5%) instead of savings accounts which are yielding less (e.g. 3%)? Is there an at-an-arms-length type of ruling for SMSF trust decisions even if it is for the advantage of the SMSF?
Interesting question but I very much doubt that would be allowed - the investment options in SMSFs are strictly regulated. If you buy an investment property within the SMSF you could use your capital as equity thereby saving in interest charges... not quite the same I know.