You are legally required to keep any detailed expense information that relates to your business & tax affairs for up to 5 years. This includes when you started the business, running, changing, selling and closing the business such as: Receipts, evidence of sales and purchases made for the business, tax invoices, wage and salary records and all documents regarding goods and services tax (GST). The ATO at any point can ask to review/audit your records so it’s important to keep everything in an efficient system, that protects all your documents from damage and being lost. Cloud accounting software is highly recommended such as XERO