Another duplex cgt query

Ppr gone from 2.5 to 6 million in 4 years.
Thinking duplex. Or maybe just large fancy house. Main thing we think what we want is to stay here in this gorgeous street (best location) BUT rebuild to enjoy luxury.

If ppr now worth 6m, then we spend 1.5 on duplex…:
Is cost base for cgt calculation (just in case we divide and sell one duplex)
NOW (6m/2) or original price (2.5/2) or something else?

also if we build a duplex and never divide it…just have kids and mum/dad, friends and nieces all living here ….we could sell it in the future without CGT…? Even though it is a duplex in appearance (not title)

 

They would be different CGT assets. ie The land, the old dwelling, the new dwelling and thats also two halves. The 4 years construction rule may apply but not to the other half ? Half the former exempt land is treated as if it was never exempt - Gulp

Hard to see how a DUPLEX is all exempt. Its not quite what a occupier buillds for themself alone. You may be creating a tax problem. Intentions to sell are a taxable issue. No CGT possibly but full income tax from isolated profit making. And also perhaps GST applies. And when you do this with one half you could also taint the "home portion" as described in TD 92/135. If you retained the home half this is less likley evident. Selling too soon poses the concern for that ruling.

Certainly a issue needing some tax advice. There would be far less tax payable if you build a new house. Live in it at least 3 months and sell it. Or just sell what you have and move into a new duplex in same area.