A breakdown of government spending has revealed a $6.6 million underspend on special education so far this financial year.
The Herald reported earlier this week that a $1.2 billion Government surplus in the 11 months to May was partially made up of a $205 million variance in forecast and actual education spending.
Figures released today show that part of the education underspend was in special education.
This is in addition to a $32 million underspend in the past two years.
A statement from the Ministry of Education's deputy secretary of people, capability and resources Zoe Griffiths said it was important to understand the figures did not include the final month's expenditure and the picture may change.
"And what's seen in these figures does not affect school budgets. They are receiving all the operational, property and other funding they would expect."
She said the special education underspend was a 50 per cent decrease on the under-spend from last year and may well come down further by year-end.
The other main reasons for the variance were teacher salaries ($27m), property ($20m), tertiary education ($47 million), and school operational grants ($6m).
The remainder - about $58m - was made up of lower-than-forecast expenditure across a range of departmental ($16m) and non-departmental ($42m) activities of which there were "no unexpected items", the ministry said.
It said it was important to note that under-spends are due to lower-than-expected demand for particular programmes.
"We do not choose or decide to under-spend".
Labour's education spokesman Chris Hipkins said it was really concerning the Ministry of Education still couldn't come up with a detailed breakdown of the underspend.
"$58 million is rather a lot of money to classify as 'other'," he said.
"The special education underspend also defies belief," Mr Hipkins said.
"There is huge and pressing demand for support for increasing numbers of kids with special needs. I simply cannot understand how the Ministry of Education can claim that this underspend is because of lack of demand."
He called the underspend in special education "incompetence".
Previously, the ministry said the underspend on special education included underspending by schools, which sometimes struggled to fill specialist vacancies.
It also had troubles recruiting psychologists for its Intensive Wraparound service.
Education's total budget is $12.7b. Of that, special education costs $350m.
The average cost of one high needs child on the Ongoing Resource scheme, which provides extra teacher time, a teacher aide and specialist support like speech therapy, is $29,000 per year.
A Herald investigation into special education this week found the demand for services is exceeding what's available, with some parents pushed to paying for their own teacher aides or resorting to homeschooling over safety fears.
It found the system was fragmented and over-complicated, with many parents struggling to get access to support for their kids.
The ministry is currently undertaking a review of special education.