Australian tax question, page-7

I guess back to the initial question if you haven't recorded the capital loss last year or in previous years that you want to offset your gains against then you will need to make an amendment to the previous years tax return or if greater than year you will need to amend all the years between so that that loss is carried through each. Generally for individuals it's 2 years that you can make corrections to returns & amend them or if greater than 2 years you can lodge an objection to extend that 2 year period. To put it simply though it's always much better to stay on top of your tax each year so it stays simple