The Treasury is to issue an update of the state of the Government's books on Tuesday morning.
The Government's operating balance at 30 June, 2008, showed the Crown was still in the black to the tune of $3.1 billion.
Radio New Zealand's economics correspondent says the latest figures are up to 30 September - and the picture is expected to be bleak.
Economists say tax revenues are likely to be depressed and welfare payments are likely to be higher, as the economy moves further into recession.
Recent losses on world sharemarkets are expected to produce an even bleaker picture once the Crown's investment portfolio, including the Government Superannuation Fund, is taken into account.
A decade of deficits was previously forecast in a pre-election summary issued on 6 October.
