Labour leader Phil Goff says his party will release full costings for its election policies by the end of this week.
Mr Goff struggled to deflect attacks from National's John Key over Labour's spending plans during the only public debate between the leaders on Wednesday night.
The Press Leaders Debate at Christ's College Auditorium in Christchurch was a sometimes fiery encounter, with the first hour focused on the city's earthquake recovery before switching to the economy - when both leaders took the gloves off.
Mr Key repeatedly challenged Mr Goff to say how he would pay for what he said were $14 billion worth of Labour Party policy promises.
Mr Key told the crowd of about 600 that Labour could not make its figures add up without extra taxes - at one point crying out: "Show me the money".
Phil Goff disputed Mr Key's $14 billion figure, but found himself on the back foot as he admitted that Labour's capital gains tax would not really kick in before 2016.
But he fired back at Mr Key, saying it made no sense for National to sell the country's best-performing assets.
After the debate, Mr Key said the campaign is all about economic credibility and is looking forward to seeing Labour's figures.
The leaders will face each other in two more debates scheduled for the last week of the campaign before the election on 26 November.