Auckland's red-hot housing market, increasingly described as a bubble by market commentators, has attracted much debate and consternation from policymakers seeking to find ways to make property more affordable.
In May, Prime Minister John Key announced a "bright line" test, making capital gains from real estate sold within two years of purchase automatically taxable as income.
That policy took effect last month, after Ms Christie agreed to sell her property, but tax experts said the new test merely hardened existing tax requirements rather than implemented new ones.
A senior partner with a major accounting firm, who requested anonymity, said it was likely Inland Revenue would look closely at the deal. "If you buy something with the intention of selling it, there's always going to be tax. The fact they're not living there is a strong indication they were just planning to sell it."
Labour housing spokesman Phil Twyford said the revelation Ms Christie appeared likely to make substantial profits from "off-cuts" from The Block NZ - a show based around contestants trying to increase capital values through renovation - but was now potentially liable for capital gains tax was a "twist in the tail" for the popular television show.
"I can't believe it. It's the perfect Auckland postscript to The Block," he said. "You'd think it was pretty black and white that she'll end up paying income tax on that whopping capital gain."
Ms Christie said while she had never lived in the property, she had originally intended it as a home for her children. She also said she was unaware of how much she would be making on the sale as she did not know how much she had spent on construction.
"As it turns out, it costs a lot of money to build houses. It's only just been completed. I don't even have the final accounts."
Ms Christie said the sale had yet to settle, and she would pay any tax she was liable for. "There's no finalised sale, but if there are capital gains to pay I will pay them."
The history of the property, on Eversleigh Rd, was featured on The Spinoff website.
During filming, the 451sq m site was used to house temporary offices for staff from Touchdown, the show's production company.
Ms Christie sold her shares in Touchdown to Dutch company Eyeworks in 2006 and stood down from the board in July 2013.
Eyeworks sold the Belmont site to an entity called MACA Trustees No1 in December 2013. The owner of MACA had been a mystery until Christie revealed in a video on MediaWorks' gossip site Scout that she was the beneficial owner. "I did the interior design myself. I just love that ranch, Ralph Lauren-y thing," she told Scout.
Ms Christie said the section had been valued independently and its unusual shape and streetside location meant any building was limited to a 100sq m footprint, depressing its value.
• An earlier version of this story, written early yesterday afternoon but not published until 4.45pm, stated that calls to MediaWorks seeking comment from Julie Christie had yet to be answered. In fact, Julie Christie spoke to our reporter between the time the original article was written and the time it was published online. The story was not updated in a timely fashion with Julie Christie's comments, and we apologise for this.