The government took in less revenue than expected from income tax, company tax and GST in the eight months ended February 29, widening its operating deficit more than forecast.
The operating balance before gains and losses was $5.5 billion, or $395 million higher than forecast, the Treasury said in a statement.
While core Crown expenditure was $1.4 billion below expectations, that was offset by core Crown revenue being $1.2 billion below its estimate.
The government's three main tax types continued to run below forecast in the first eight months of the year, the Treasury said.
Source deductions were $200 million below forecast "as the labour market and employment and wage growth have been weaker than expected," the Treasury's chief financial officer Fergus Walsh said. Corporate tax was $193 million below forecast "as business profitability was weaker that expected," he said.