Labour has sensibly un-done what it should never have done in the first place - reserving the right to make huge changes to the tax system between elections.

It has been the only disastrous part of Labour's campaign and was executed badly from the start.

The U-turn was made today with more clarity than the first U-turn.

There was never a formal announcement by leader Jacinda Ardern or finance spokesman Grant Robertson that the party had ditched previous leader Andrew Little's commitment - a highly principled position of putting any major tax working group changes to the 2020 election.

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That information was eked out in media interviews, three weeks after Ardern became Labour leader.

She dubbed it a 'captain's call' but the fact is she would never have done it without the support and encouragement of her closest advisers, including Robertson.

Undoubtedly, the calculation among her advisers was that if the momentum behind Ardern was extraordinary enough to propel her to the Prime Ministership within eight weeks of becoming leader, then she would have some extraordinary political capital to expend.

And they decided that that would be the option to introduce a capital gains tax next term. It was an extraordinary political risk that backfired.

It may have initially been seen as a way to introduce a capital gains tax (CGT) without having to wear the damage of promising to introduce it - as Labour had in the past two elections.

But in the end the damage of not admitting its real intentions has been more damaging than had it ditched Little's position and just plainly said it was definitely going to introduce a CGT and the working group would work on the details.

It was a hopeless strategy because it dented Ardern's credibility needlessly.

She said the tax working group might come back with no recommendation for a capital gains tax, but that was not believable.

She said she was being very transparent about a capital gains tax when the opposite was true.

Over three elections Labour has had three positions on capital gains tax: a. to introduce a GCT; b. to introduce a CGT but only if it gains a mandate at the 2020 election; c. to maybe introduce a CGT but before the 2020 election; and now back to Plan B.

If it had stuck to the principled Plan B from the start, and not tried to take advantage of Ardern's popularity, it would have done itself - as well as voters - a favour.