If you use information about tax losses in a later tax return – for example, 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.
For more information, see 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?