"We will review and revise those targets once we are in Government and we'll see where we get," said Robertson.
"The last time Labour was in office we got debt down close to zero so of course we are in favour of reducing debt."
He said the numbers Joyce had "plucked out" for the 2025 target was where Treasury's longer term forecasts were going anyway.
National increased the debt as a result of the global financial crisis and the Christchurch earthquakes from 5.4 per cent of gdp in 2008 to 24.3 per cent now. The deficit peaked at a record $18.3 billion in 2011.
Joyce said he had revised the debt target to ensure New Zealand was better prepared for a future shock.
"The impact of those two events, the earthquakes and GFC, and the decisions we made to support people really used up 20 per cent of gdp's worth of debt and that is very fresh in our memories.
"Then something like Kaikoura comes along and reminds everybody that actually, there's no rule against another one. "
So for that reason and the fact that 2020 is now approaching, and we are on track t do it, we need to start talking about what the plan is post 2020.
Meanwhile New Zealand First leader Winston Peters says the Government will present a surplus on Thursday only because it has underfunded many public services including in health, education, police, conversation and housing.
"The Government will have to explain how there is a surplus after addressing all the reasonable demands that need money spent on them," he said.
"If this Thursday's Budget does not do that, then claims of a surplus will be without credibility, plausibility or integrity."
