Finance Minister Bill English says the country is probably facing the biggest cash deficit a New Zealand Government has ever had.
The Government's books were in the red by $10.5 billion in the year to June, a deterioration of $12.9 billion compared with the previous year.
A deficit of $9.3 billion was forecast in the Budget in May.
Mr English says the Government will have to borrow $250 million per week for at least the next four years to maintain public services.
He says it could then take up to 20 years to repay the debt.
Tax revenue last financial year was down by almost $3 billion from the previous year, while spending was up $7 billion.
