Building a new duplex on the family home block: What tax do I have to pay?

Building a new duplex on the family home block: What tax do I have to pay?
Building a new duplex on the family home block: What tax do I have to pay?

Hi Margaret,

I currently live in Sydney and on a 970 square metres property, and have been for 27 years now. The property is located approximately 20 kilometres from Sydney CBD.

I am thinking to knock down my existing home, building a duplex and then selling one to finance the construction costs for both. Thereafter, I intend to live in one of them.

What is the taxation implication on my current and future property (i.e. one of the duplex I plan to live in)? Will I pay tax on both properties? What tax (and deduction) do I need to pay for one of the duplexes I plan to sell?  Can you provide a sample taxation calculation? Is there a correct procedure to minimise my tax?

Thanks in advance.


Margaret's answer on the next page. Please click below.

Hi Dave,

If you subdivide a block of land, each block that results is registered with a separate title. In terms of capital gains tax (CGT), the subdivision means that you will end up with two separate assets. Subdividing the land does not result in a CGT event if you retain ownership of the subdivided blocks and this means that you don’t make a capital gain or a capital loss at the time of the subdivision.

You are intending the demolish the family home, leaving you with a vacant block. As you bought the original property 27 years ago, you may trigger CGT once you erect the new dwellings and sell one. Your principal place of residence exemption can be applied to one property (likely the one you live in) but the second dwelling will incur CGT.

The date you acquired the subdivided blocks is the date you acquired the original parcel of land and the cost base of the original land is divided between the subdivided blocks on a reasonable basis. Then, the cost of erecting the dwelling on the block you intend to sell will add to the original assessed value of the newly created block to create a cost base for that property.

Once you sell you will be charged CGT on any profits you make. As long as the new house and land is kept for 12 months from the contract date to build the new house, then the 50% discount will apply.

I chatted to my Property Success tax expert, Ian Rodrigues, about this and he said that I should add that practically any gain is likely to be in the land, not the building, in such a short time frame. Even over time, most gain is in land and not building value, but it is a matter for a valuer to split the amounts to establish which is worth what.



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Margaret Lomas

Margaret Lomas

Margaret Lomas is a best-selling author and writes and hosts the popular Property Success With Margaret Lomas and Your Money, Your Call, both on Sky News. She is the founder of Destiny.


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