Ministry of Education figures show teachers have claimed more than 183,000 sick days so far this year, nearly twice as many as at the corresponding time in 2019 - the year before the pandemic.
To cover those teachers, schools have hired relief teachers for more than 171,000 days, slightly more than in 2019.
Tirimoana School principal Peter Kaiser said the school had already spent more than its entire annual budget for relief staff.
"It has been exceptionally difficult, both in my school and in schools around me in West Auckland," he said.
"For the first four months of the school year, so February, March, April, May, we have already spent 160 percent of our annual budgeted funds for relief teachers for sick cover."
That was about $40,000 and it would be even higher but for that fact that on some days he could not find relievers when he needed them, he said.
Kaiser said continuing children's education was top priority so the school would keep paying for relief teachers using money it had hoped to use for other things.
"Either the school will end up with a significant deficit at the end of the school year or it will be that planned expenditure in other areas have had to be dropped to cover the relief teaching blowout costs," he said.
He said this year was the most difficult he had ever experienced in his 30 years as a principal.
Kaiser said the ministry had extra funding to help cover the cost of staff absences caused by Covid, but it was time-consuming to apply for and would not cover absences caused by other illnesses.
Western Heights School principal Ash Maindonald said he normally saved a portion of his staffing entitlement, about a quarter of a full-time teaching position, for use in the final term of the year.
But this year, he has used that and more to cover sick teachers.
"This year all of that staffing that I have been saving up and would have saved has already gone and I've spent $26,000 more on staffing than my total annual allocation," he said.
Other funds used to pay relief teachers
Maindonald said he would to use funding set aside for property repairs to pay for relief teachers.
Principals Federation president Cherie Taylor-Patel said the ministry was paying for any relief teacher costs beyond the first four days of a teacher's absence, which was more generous than normal, but it was still not enough.
"You have more people who are sick and they're getting sick again, and again. So while it is great that schools are only having to pay the first four days of a person who is not there, it has still had the impact on relieving budgets," she said.
"Principals are lying awake at night worrying about how they're going to keep their budgets intact for the rest of the year."
She said schools needed more money to cover the cost of relievers this year.
"We need the government to urgently review and look at the relieving budget, particularly around sickness and to perhaps look at how they can top schools up between now and the end of the year so we don't have massive budget blowouts right across the country, which is where we're heading at the moment," she said.
The Education Ministry's hautū (leader) operations and integration, Sean Teddy, said it was aware the higher-than-normal demand for relief teachers was putting pressure on schools' operating budgets.
"Where a school or kura is experiencing high levels of staff absences due to covid, or other illness, they can claim Additional Relief Teacher Funding (ARTF). We provided additional support in term 1 and have increased that support with extra funding for the current term, through the relief teacher fund," he said.
Teddy said schools might have other entitlements or financial reserves to manage their relief costs.
"Where schools and kura are experiencing financial difficulty, we encourage them to make contact with their School Finance Adviser to provide assistance and guidance," he said.
"Staff in our regional offices are working with principals every day to help them find solutions to their specific staffing needs. We encourage schools to reach out to their local Te Mahau office if they are facing staffing challenges."
