It is a legal requirement, Chapter 2M of the Corporations Act...

It is a legal requirement, Chapter 2M of the Corporations Act mandates that companies prepare and lodge annual financial reports with ASIC.
The reports must be audited and include a financial report and a directors report, they must be lodged with ASIC and within 4 months of end of financial year. It is also a requirement for the Company to provide a copy of the report to be sent to all shareholders.

Unlisted disclosing entities are required to lodge half-yearly financial reports with ASIC. These are generally an abridged version of the annual financial statements and are due within 75 days of the end of the half year, the half year report is not required to be sent to members.

Section 250N of the Corporations Act mandates that public companies hold an Annual General Meeting each calendar year and within 5 months of the end of the financial year.