You are spot on, grubarura. These shareholders are categorised as not earning enough to pay tax (below the threshold). Yet they are forced to pay tax on their dividends - and to make matters worse they will be paying at the company rate of 30%. There is no way they are going to invest in fully franked Australian companies. A lot of this investment money will go overseas, especially as it is so easy to trade overseas shares now. Alternatively it will go into Australian companies that do not have a franking policy. Either way, as you say, there will be a massive BLACK HOLE.
