tax on capital gains, page-12

You need to account for closing stock (shares still held), which can either be valued at cost or market. You usually use market value when it is lower than cost.

As an aside 30 trades is not that many, however there are other factors to consider when saying you are a trader. Your activities must be in the nature of a business. Here is a good start https://www.ato.gov.au/General/Capi...ents/Carrying-on-a-business-of-share-trading/.

Cheers