Some coys (e.g. BEN and HIL) allow shareholders to elect to forego dividends and receive bonus shares instead. This is known to be a very good idea if the original shares have been held since 19/09/1985. However the tax treatment of bonus issues on top of post-85 original shares is not clear. My interpretation based on BEN website and HIL booklet is: (1) no franking credits (2) no liability for income tax (3) cost base for CGT is effectively zero (4) CGT payable on disposal (at 50% discount if held for more than 1 year after bonus issue)
The ATO website is not very helpful -- it seems to more or less agree with the above but then it also says that if the bonus shares are received instead of a dividend then they are taxed just like a dividend.