Keep records longer for losses

You must keep proper records relating to your tax affairs for at least five years.

If you use information from those records in a later tax return, you may have to keep records for longer. So, if you carry forward a tax loss, you must keep the records until the end of any period of review for the income tax return in which the loss is fully deducted.

See also:

Taxation Determination TD 2007/2 – Income tax: should a taxpayer who has incurred a tax loss or made a net capital loss for an income year retain records relevant to the ascertainment of that loss only for the record retention period prescribed under income tax law?