Finance Minister Bill English says the growth of Government assets, especially the ACC investment fund and the so-called Cullen super fund, could have an unpredictable effect on the forecast surplus.
The Government's half-yearly accounts, to be unveiled on December 17, would still forecast a small surplus and the Government was still committed to achieving it in the 2014-15 financial year, he told reporters at Parliament yesterday.
But the fact that the funds were so big meant that small changes, for example to interest rates, could have a big impact.
Over the past five years the ACC investment fund had increased from $9.6 billion to $24.6 billion and the New Zealand super fund had increased from $14 billion to $23 billion (even with Government contributions suspended).
"The ownership of this wide range now of financial instruments through the investment funds and the big liabilities associated with the earthquake just make it a bit trickier."