The Government's books have taken a turn for the worse, with spending exceeding revenue by $5.3 billion in the nine months to the end of March.
The figure compares to an operating deficit for the eight months to the end of February of $4.5 billion.
Tax revenue was $530 million lower than forecast at the time of the Treasury's half-year fiscal update in December.
Corporate and personal tax revenue was lower than expected in December but GST was 3.7% higher.
Once unrealised gains and lossses on the Government's investments are included, the deficit was $1.3 billion, compared to a $1.6 billion deficit including gains and losses for the eight months to the end of February.
The Government's cash deficit for the nine months to the end of March also worsened compared to the eight-month period.
