Records you need to keep – ATO

To prepare an accurate tax return you need to keep records that support the claims and declarations you make. As a rule, it is better to keep too many records rather than not enough records.

The Australian tax system relies on taxpayer’s self-assessment. This means you are responsible for working out how much you can declare and claim on your tax return. You also need to be able to show how you arrived at these figures – in some cases, we may require you to provide written evidence

For further information click here

Source:  https://www.ato.gov.au/Individuals/Income-and-deductions/Records-you-need-to-keep/