correct clary 100%

I think sellers get confused with gst against income tax. 2 different things , so forget about gst  its not what this is about.

once you have brought and sold something in a shop or online anywere ebay ,website,market.anywere.its taxable income ,your profit only. even if its $1, now at the moment anysales you do over $10k a year ,by law gets sent to the ato,unless you are selling only your own seconhand goods,must be entered in your taxable income , if you sell under $10k a year you still have to declare it by law ,but the ato do not have your info , but at anytime they can ask ebay or whoever i want details for bla bla Id. 

no diference if you are a pensioner or on benefits where you can earn so much before your payment are affected , selling is income ,unless its your own private goods.