The 6 year exemption was simply to allow anyone who owns a home to move out for a period of time and maintain the main residence status. The view was to not disadvatage a person teporarily moving for work purposes
If you contract a builder to build your new home YOU MUST live there for 3 months for the property to be exempt
If it is an established property you must have either lived in the property or be able to prove a strong case the intention was to live in the property at the time of purchase
the type of things that are looked at to comfirm main residence status are: