Assuming the property in question is the only dwelling you own in Australia, it is automatically afforded the Capital Gains Tax (CGT) exemption as it is considered your 'main residence' for tax purposes.

Every taxpayer can have a nominated main residence but can only have one at any given time.

Whilst you are overseas, you may want that residence to be regarded, for CGT purposes, as your main residence while you are away. As you wish to rent out the family home, you can choose to treat it as your main residence for a period of up to 6 years and the main residence CGT exemption will continue to apply for that period.

However, should the period of absence and income producing exceed 6 years you will then become liable for CGT on disposal of the property for that period of excess. This is calculated on a pro rata basis using the period of CGT liability as a proportion of your total ownership period.

How the rental income is treated will depend on your Australian tax residency status whilst you are away and the net income amount (rental income less expenses). One can either retain their tax residency status whilst away or be treated as a non-tax resident. Your status depends very much on your personal circumstances and intentions. Professional advice should be sought in determining your Australian tax residency status.