To be a trader you don't need an ABN. I've been one for over 10 years and have never had to get one. You can still treat trading as a business though and fill in the business section of your tax return. However in order to do that your yearly turnover (total sells) needs to be over $75,000 which is quite easy to do as a trader. Then any expenses you incurred can be listed in your tax return as business expenses. Some of mine were MS Office subscription, computer repair etc... There are some people who have an account for investing and an account for trading usually with seperate brokers. It's a coincidence actually because we're discussing it on another forum whether you can be both or not. I'm solely a trader but in my mind I think you can be both a trader and investor, in your tax return you couldd fill in the business section for your trading and then the personal investments sections for your long term invesments. Something to check with the ATO\tax professionals if you were pursuing it.
You're probably right that if you have lots of gains then there are benefits to becoming a company because companies pay less tax, but then there are added complications and regulations you have to follow.
One thing that one of the Heart posters used to do was somehow use a trust for shares. That way even if you have some bad years and some amazing years, everything gets treated the same at the same tax rate.
