Prime Minister John Key says a capital gains tax is one of the "third rails" of politics in New Zealand - and anyone who touches it will, in political terms, be killed instantly.
This week Labour touched that rail and received only an invigorating tingle rather than the shock of their lives.
This is good because it shows New Zealanders can look beyond the headlines to the underlying need for structural reform that reduces the tax subsidies for property investment.
The debate is welcome, but Labour could have done much better and should be trumpeting how such a tax would shift investment into more productive export industries and create higher-wage jobs to keep young New Zealanders here.
Instead, it has watered down that message by proposing a capital gains tax that is full of exemptions and then used the revenues to shuffle tax from the very rich to the poorest.
A capital gains tax is a good way to change the incentives for investors and reduce our appetite for foreign debt-funded domestic consumption.
But it would be better if it raised considerable amounts of tax and was difficult to avoid.
The exemptions for the family home, for residences in family trusts, for Maori land, collectibles and gambling winnings will be welcomed with open arms by budding tax accountants and lawyers.
These will be high-paid jobs, but they're not the sort we want.
A land tax would have been much more efficient, simple and lucrative.
The idea put forward to the Tax Working Group in late 2009 by Motu economist Arthur Grimes for a 0.5 per cent land tax with a $50,000 a hectare tax-free threshold and the ability to defer payment until sale would have raised about $2 billion a year.
Labour's capital gains would initially raise just $18 million in its first year and take 10 years to get to $2.3 billion a year.
Capital gains does nothing to rectify the intergenerational wealth transfer created by the doubling of house prices in the property boom from 2002 to 2007.
That created more than $300 billion in wealth for a generation of property owners and means the generations to follow will have to take on huge debts to afford a family home, particularly in Auckland.
The property boom has shifted wealth in the form of future debt repayments by the young into equity gains now for the old.
A capital gains regime that is not retrospective locks that shift in place and punishes future generations for any capital gains they make. And exemptions for small businesses mean baby-boomer owners wanting to sell to younger generations will get to keep those capital gains tax-free.
But the biggest problem with Labour's tax package is not the tax. It's a lack of spending cuts or any real and new reduction in foreign debt.
Labour's deficit and debt track is little different to National's and any gains from capital gains and the 39c tax rate are being redistributed to low-income earners rather than to repay debt.
Labour makes a lot of noise about "owning the future", but hasn't addressed the need to reduce borrowing. That is the major reason we are getting poorer through interest payments to foreign creditors.
High borrowing by our government and property owners also makes us poorer in the long run through a ruinously high currency that hollows out the value-added jobs needed to keep our younger generations here.
Labour needed to press harder on that third rail to get a bigger jolt.