It's often difficult to know what information to keep and for how long, so here's our quick summary of the current Australian requirements:

1. The minimum period for retention of any annual company compliance documents as per ASIC regulations is seven years. This would typically include financial statements and receipts. However, your company corporate secretarial records such as constitution, minutes, resolutions etc are part of the permanent records and need to be maintained and kept for the full life of the company and seven years after deregistration. In most cases we act as the registered office for our clients and retain the permanent records on your behalf, however, if you choose to be your own registered office, this is an additional responsibility for you to manage. Read more here
2. The ATO requires all documents supporting the lodgement of income tax returns to be kept for five years from the date of lodgement unless you are being audited by ATO. Remember the five year period starts from the date of assessment of your income tax return,  so you if lodge your return late you have to keep the records for five years from the date that return is assessed (for individuals when your notice of assessment is issued) or lodged (for all entities).  Full details here

Therefore, from a practical point of view, we recommend that you keep everything at least seven years, unless:

• It supports the cost base of a business or investment asset, as you will need to keep all records supporting this for seven years after the asset is disposed of.  So if you still have an asset which was purchased twenty years ago, you still need to keep those full records in case of a future capital gain; or
• It is an item being depreciated or written-off for a period greater than seven years; or
• It is an unusual or contentious issue.

As electronic storage space is getting cheaper and cheaper we recommend PDF or other backups of all your data for at least seven years. If you want to be conservative keep a rolling record for the last eight years, then you can destroy the earliest year when the next year comes around.  A full list of records to be kept can be found in the links provided here to the ASIC website, and here to the ATO website.

PS for any purchase you should always hold a valid "Tax Invoice", remember if it is an asset purchase it is recommended that you keep this as proof, in addition, any documentation for additions or improvements to the asset for the full period of ownership and seven years after disposal. Check the requirements for tax invoices here