"But from 2017/2018 we will be paying back the debt faster than a National Government would because of the ongoing asset returns and the increasing revenue of our fairer tax package", he said.
Finance spokesman David Cunliffe said the fiscal strategy "is an integral part of a broader economic plan that will address the underlying structural problems facing the New Zealand economy: high private debt, low savings, over investment in property and an aging population."
Turning to National's attack that Labour's plan would see $17 billion more in borrowing under a Labour Government, associate finance spokesman David Parker said National had not recognised the loss of dividends from selling half stakes in state owned enterprises in its figures - money that Labour would keep.
Labour had also counted the money borrowed for $6 billion in NZ Super fund contributions as neutral in terms of net debt as the money resulted in a corresponding asset.
The other big item was the difference in view as to what gains in tax revenue could be made by ring fencing losses on property investments.
Labour, this morning, as National has done, claimed their numbers were based on Treasury advice.
Labour's number were criticised by National, with Mr Key saying Labour was not accounting for $6b it wanted to put into the Cullen Fund.
"If you take the New Zealand Super fund, for example, he's saying if you have a mortgage against your home, that [debt] doesn't count and the day you buy the house, you should book the profits of what you think you might be able to sell the house for some time in the never-never.
"And he's wanting New Zealanders to believe that's real, at a time where we're living through the most volatile financial markets and stockmarkets in the world.
"It might be a form of economic management that Greece is happy with, but it will not work in New Zealand."
He said Phil Goff was trying to pull the wool over the public's eyes with some "mythical profit".
"If it's such a great idea and so guaranteed despite the fact that the world's stock markets are more volatile now than ever before, why doesn't he go and borrow $100b? Is he telling New Zealanders that when they borrow money against their house, it doesn't count, and they should go and spend the money today that they might one day make, even though they don't know what the property market's going to be like in four years' time?"
Mr Key again played the "I spent my life as an investment banker" line to talk up his financial literacy.
"The definition of borrowing is where you issue a bond. Ask Phil Goff if he'll be issuing bonds for $4b, or a lot more than that."
He said restoring ECE centres to having 100 per cent trained staff would cost $400m a year, and the Government only has $800m in new operating money a year.
"Their numbers don't add up. They're using a Greek calculator."
"Anyone with a probably form 2 level understanding of accounting " could see that Labour was borrowing at least $10b.
"Whether it's ultimately $14b or $17b, I don't know, but if it's $4b, I'm a monkey's uncle ... It really is farcical."
He said he would not borrow to put more money into the Cullen Fund, and would wait until returning to surplus before doing so.
