A budget blow-out across District Health Boards has grown by a staggering $112 million, or 36 per cent, in a single month to more than double what it was the same time last year.
All but one of the country's 20 DHBs were in the red for the 11 months to May, with their total deficit rising to $423 million, latest financial results from the Ministry of Health show.
At the same time in May 2018, the deficit was $204 million.
It's now expected the total deficit by year end, in June, will be $508 million - compared with Treasury and Ministry forecasts of $390 million just months ago.
The Ministry noted budgets were expect to take major one-off hits for compliance with the Holidays Act and write-offs of its troubled National Oracle Solution IT system.
And it says those cost estimates are "conservative" and could get worse as some boards had not yet factored them in.
The figures were published on Friday after Health Minister David Clark was accused of stalling their release.
In its report, the Ministry also attributed the situation to personnel, service, clinical supply and infrastructure costs, and payments to other providers.
South Canterbury District Health Board was the only authority to break even.
DHBs are struggling with rising populations and growth in the number of patients requiring more complex health services, higher personnel costs and ageing infrastructure that requires a large cash injection.
Friday's financial information showed the health boards had under-spent on capital by $222 million, from $597 million in budgeted expenditure.
In a statement, Clark said the shortfalls were the result of years of underfunding by the previous government.
But he said the Government did not accept deficits were inevitable.
"Some DHBs manage to post small surpluses, break even or only post small deficits while maintaining services. It can be done," he said.
"DHBs have been directed to ensure they improve on their underlying deficit position in their 2019-20 planning."
The Government had put up $695 million of extra funding for DHBs in this year's Budget along with capital funding for cash-strapped boards, he said.
The 20 DHBs were given $13.98 billion in May, compared with $13.24 billion last year.
Clark has previously warned them to tighten their belts.
National Party health spokesman Michael Woodhouse said it had been clear for some time the deficit would grow and the Government had not invested enough to make up for pay increases in the sector.
"If you are going to load the sector out with that level of cost increase, you have to fund it. And [Clark] didn't. He's underfunding health in a way he accused the previous Government of," Woodhouse said.
Earlier this week, Woodhouse accused the Minister of holding back the figures because they showed the Government was failing to rein in the deficits.
While Clark received the data on June 21, he officially refused to release it to Woodhouse last week.
The Minister told reporters he had not been aware the information had been sitting in his office for six weeks and would immediately sign it off.
Woodhouse on Friday said he was "flabbergasted" the Clark could be holding such significant data for six weeks without reading it, describing it as negligent.
The Auditor-General in June raised concerns that in only a few years to 2018 the situation had deteriorated from just a handful of DHBs being in debt to the vast majority.