If you don't dispose of the former home property by 12 months after vacating it and moving to your new home then some portion of any eventual resale gain will be assessable for CGT. For example, if you had lived in it for 6 years, and hold onto it for a further 5 (i.e. 11 years ownership in total) and then sell it then (11 - (6 + 1)) / 11 = 4/11 = 37% of any eventual resale gain will be assessable for CGT. This is definitely the case if you rent the property out. However I am pretty sure that it's the same even if the property is not rented out. If you rent the property out within 5 years of purchase as an owner occupier then a clawback of stamp duty will also apply. If in doubt get independent, professional advice on the tax issues involved.