You must keep all the records, receipts and other documentation you have used to prepare your tax return. If you are claiming deductions, you must keep written evidence to verify your claims for those deductions.
If you are an individual, you must keep proper records relating to your tax affairs for at least five years from the date you lodged your tax return.
If you are a small business, you must keep proper records relating to your tax affairs for at least five years from when the business record is prepared or the transaction is completed, whichever occurs later.
If at the end of the five year period, you are involved in a dispute with the Commissioner (an audit, for example), the five year period is extended.
If you use information from your records in a later tax return, you may have to keep records for longer. So, if you carry forward a tax loss, you must keep the records until the end of any period of review for the income tax return in which the loss is fully deducted.
If you own an asset which will be subject to capital gains tax on disposal, you will need to keep records covering the entire period of ownership until 5 years after lodgment of the tax return recording the disposal of the asset.