Its best to check the relevant legislation
the 6 year rule, s 118-145 ITAA 1997
http://www.austlii.edu.au/au/legis/cth/consol_act/itaa1997240/s118.145.html
The 6 month overlap rule, 1 118-140 ITAA 1997
http://www.austlii.edu.au/au/legis/cth/consol_act/itaa1997240/s118.140.html