Health New Zealand has ordered an immediate hiring freeze on all non-frontline roles.
The directive was laid out in an email sent to all staff on Thursday and leaked to RNZ.
In the email, chief executive Margie Apa told staff the recruitment freeze applied to all hospital roles that did not deal directly with patients and all public health jobs that did not deal directly with the community.
The only exception was for those people who were offered a verbal offer or a contract before midday on Thursday.
Apa said the measures were aimed at reducing overspending.
Health NZ had made "significant advances" in recruitment in recent months.
However, "this comes at a cost where we find ourselves spending over our current year budget", she said in the email.
That was especially true in hospital and specialist services where more nurses had been hired, she said.
The freeze would be in place until at least when the budgets were set for the next financial year.
"These new measures will not impact frontline services," Apa wrote.
"Staff and patient safety and clinical delivery remain our priorities and will be considered when making decisions on which roles to progress."
All candidates going through the recruitment process, who had not been issued a contract or verbal offer, would be told that recruitment was "pausing at this time", Apa said.
"I know that these changes will raise some questions, perhaps more so for those in areas where recruitment is being paused," she said.
"Please talk to your manager about how your teams will manage any change in your area.
"Thanks for your support in this ongoing effort to keep us within budget while still maintaining vital frontline services."
Health New Zealand has been contacted for comment.
Earlier this year, the organisation ordered a ban on double shifts in a bid to cut its operating costs.
It also asked managers to review unfilled roles in their teams and "consider permanent removal of these as part of the budget processes".
However, Apa said at the time it was not a hiring freeze.
"Particularly where if you've had roles that have been vacant for [a number of months] and you've been able to function as a service, I think it's reasonable for leaders to check whether they need that role or whether they need the job carried out in the same way that they might've assumed when they thought they needed that role."
She said staff were being reminded of "some of the things we need to do to ensure we live within our means.
"We need to make sure we're as efficient as we can be in our day-to-day operational practices."
Health NZ also introduced changes to recruitment back in April, saying no new hire was to start on in a non-clinical role before 1 July without top-level approval, and only at existing rates.
RNZ