Your online billing information goes back as far as October 2011. You can find a bill using AGL Energy Online by selecting 'Billing and Payment Summary' under 'My Energy'.
If you need a copy of an older bill to be mailed to you, go to the ‘Help Centre’ under 'My Energy'. From the drop-down options under ‘Create New Energy’, select ‘Billing’ and ‘Bill copy request’. Follow the prompts to ‘Proceed with enquiry’, then enter the billing period – e.g. 01/08/2010 – 30/08/2010 – to order your copy.