Can you advise how to calculate the Capital Gains Tax on a rental investment property?

Q.

Try as I may via the ATO website and other sources I can't get a clear understanding of the way to calculate CGT on a rental investment property that was my principal place of residence for part of the time. I bought a property as an investment, occupied it for two years as my home, then it became an investment rental property again. Can you advise how to calculate the CGT on this?

On the facts provided you bought the property as an investment, rented it out for a period, lived in it and then re-rented it. If this is the case you are liable for CGT on the pro rata basis based on the number of years you lived in it. For example, if you owned the property for eight years and lived in it for two you would pay CGT on 6/8ths of the gain. You can also take advantage of the 50% discount as you have owned the property for more than a year.