Questioned further, Labour told a television journalist it was based on an average uptake of four months per person. She reported that, along with the observation Labour's numbers did not add up for a six-month scheme.
That sparked a three-day war as Labour's Phil Twyford took to Twitter and then in person to deride the report as biased, a "hatchet job" and "unprofessional". What riled Labour was the claim it had botched its numbers (not helped by National minister Steven Joyce's quip when told of the difference: "asterisk: may contain nuts.").
As it transpired, Labour had not botched its numbers. It promised a six-month scheme but costed a scheme of "up to six months" and probably more like four months for most people.
At best it created confusion. At worst, it was misleading. It was certainly unnecessary.
It is no surprise Labour was defensive on the issue. It has to convince the public it can be trusted with numbers. Labour's costings have been a sensitive topic since 2011 when John Key wiped the floor with Phil Goff in a leaders' debate with the Jerry Maguire phrase "show me the money".
That cast a long shadow which vexed two more Labour leaders after Goff and is now niggling at a third.
So the surprise was that Labour put itself in a position to be questioned over its costings at all. The whole brouhaha could have been avoided by simply including the relevant assumptions in the material distributed.
Labour was supposed to have learned this lesson in January 2014 when former leader David Cunliffe set out a "Best Start" policy.
The centrepiece was a $60 a week payment to parents of newborn children which Labour claimed was near universal and would benefit 59,000 families a year.
It was not until the next day media found in the fine print that nobody on paid parental leave would get the payment. That took out 25,000 families and rather reduced its universality.
As a result David Parker, Labour's finance spokesman in 2014, made a determined effort to disclose detailed costings of policies for the campaign.
Despite that, the best Little could say, when asked why he had not mentioned the work scheme costing was based on four months, was to claim the media did not subject the Government to the same scrutiny.
He was not alone. Twyford and Grant Robertson made similar complaints.
Cry me a river.
In politics somebody will always catch out misleading or incorrect claims, whether they happen by conspiracy or cock-up. If it is not the media, then both Labour and National have staff dedicated to doing just that - running the rule over the other side's costings.
On Monday, Social Housing Minister Paula Bennett got a similar grilling over the $300 million she had just announced for emergency housing for the homeless.
Bennett's grilling was because she was guilty of the same sin Labour now stands accused of - she had glossed over a pre-Budget $41 million announcement to fund 3000 emergency housing places.
At first blush that appeared to be for extra beds, not least because Bennett described them as "new". Upon further probing, it was discovered they were not extra beds at all.
Cue cries of "misleading" from the Greens and Labour, and Bennett was forced to clarify.
But today Labour will have moved on to bigger battles.
The United States elections reportedly prompted a 141 per cent increase in Americans searching New Zealand property listings on realestate.co.nz.
Labour's team will be calculating likelihood ratios on a list of American-sounding surnames for phase two in its campaign to save the New Zealand first-home buyer.
