The cost of junior doctors doing extra hours to plug workforce shortages has skyrocketed to more than $70 million a year.
The costs for 2022-23 were more than twice as high as the year before when they were $33m, figures generated for RNZ by Te Whatu Ora show.
They were also 2.6 times higher than the $23m paid in 2020, when doctors worked long hours to tackle the Covid pandemic.
Health NZ was forced by big gaps in the rosters to virtually double the rate it paid per shift in June 2022.
"My reaction when I saw the figures was: 'Wow, it really is that bad'," said Resident Doctors Association (RDA) national secretary Dr Deborah Powell.
"They were new figures to me, but with 400-500 vacancies of resident doctors, they also weren't a surprise."
Health NZ agreed to pay almost twice as much per hour in mid-2022 for "additional duties" that saw junior doctors doing evening, night and weekend shifts on top of their regular work hours, as well as a much smaller amount for "cross cover" work to plug gaps in day-time shifts.
This higher rates were meant to stop last month, but were continuing.
"There are still gaps as some shifts and services have not been able to cover the gaps," Health NZ said in the OIA supplied to RNZ.
Shifts to cover out of hours had historically been hard to fill.
"The enhanced payments were to recognise that we needed cover for those shifts."
Powell said it was a "vicious cycle", with plugging gaps at high cost taking money away from regular pay rises needed to help retain staff.
"It did take an increase in the rates to get them to do the cover," she said.
"But they don't want to. They already work 60 hours a week... they don't want to suffer the consequences of fatigue and make a mistake."
She said junior doctors were not taking advantage of the system. "No, the residents [junior doctors] know that we have to cover the shifts, otherwise there won't be a doctor".
Health NZ took over a year to give the junior doctor information to RNZ; it should by law take five weeks.
"I am very sorry for the delay," wrote Sasha Wood, head of government services.
The high costs increased pressure on districts that received orders from the government last month to find $105m in savings from staffing by the end of June.
"The higher rates are higher than budget, which will impact on the bottom line," said Whanganui district about the junior doctor rates.
The 2500 junior doctors in the Resident Doctors Association are taking industrial action over pay.
A strike on Tuesday is set to be followed by a two-day strike from next Thursday morning. Senior doctors have often had to cover for them.
Most have been offered a 20 percent pay rise, but not all - others would get a 12 percent pay cut, creating a split that has motivated strikers.
"We are such an undervalued but integral part of the hospital," a Waikato Hospital medical registrar on a picket said.
OIA figures show some districts paying more than twice as much between financial year 2021-22, and 2022-23. Northland paid almost four times as much - $3.2m versus $840,000 - Waikato paid 3.3 times more and MidCentral's costs were 2.6 times higher.
Capital and Coast paid 2.3 times more, and it also topped the total costs in additional duties and cross-cover of any district - $13.4m, a rise of $7m in just 12 months.
This was well ahead of Canterbury ($10m) and Auckland ($8.7m).
The beleaguered Southern district had to find an extra $2.27m to cover the extra pay for junior doctors that it had not budgeted for.
While the higher rates had helped plug gaps, "workforce shortages" and higher rates of unplanned leave by both junior and senior doctors, had weighed the other way, the OIA showed.
This was reflected in the Hutt, Capital Coast and Wairarapa districts stating: "While these rates add to the district's overall wage and salary costs, this is offset by the districts' RMO [resident medical officer] vacancy rates."
Vacancies were the problem, Powell said.
"If we can solve our retention problems, we won't need to pay this money.
"An investment to get the retention correct will be rewarded by not having to pay this money and overall we will be in a much better situation financially - and having enough doctors to look after our patients."
Health NZ chief people officer Andrew Slater said in a statement that workforce pressures were being felt on the front line "and these shortages are having an impact on our people".
"We acknowledge their contribution and commitment to serving their patients and communities," he said.
"We can't fix those shortages quickly."
An extra 50 new medical school places were being opened up from this year as a "first step" to boost local training, and a support service for junior doctors was being developed, Slater said.
In the OIA, Te Whatu Ora said there was no evidence of junior doctors gaming the system - such as by using lieu days with the agreement that a colleague would work for them, and collect the higher additional duties pay, then requesting their own lieu day.
A joint agency-union group met to ensure any breaches were clamped down on and "it was not raised by either party as a concern or practice being witnessed".