The pandemic and the government's $64 million donation scheme combined to cut roughly $170m from schools' locally-raised income last year.
The Education Ministry figures for 2020 do not include the accounts of 232 schools but, even allowing for that omission, they show significant declines, especially in the amounts collected for school trips and activities and from fundraising.
The numbers indicate schools' income from sources including foreign students, general donations and donations for activities and trips fell about 28 percent last year.
Extrapolated across all state schools, that would equate to a drop in income of about $40m from foreign students and about $130m for locally-raised funds.
That was offset by a $20m bailout for schools that lost income from foreign students, and $64m from the government's donation scheme, which gives schools in deciles 1-7 $150 per student if they stop asking for general donations and donations for some activities.
The figures showed schools that were not eligible for the donation scheme, those in deciles 8-10, suffered a drop in donation income last year.
Meanwhile, the scheme did not stop donations altogether for schools that were in the scheme. The eligible schools that reported figures to the ministry made $29m in donations last year and $52m from donations for school activities.
Fundraising income also fell in both groups of schools.
The principal of Mairehau Primary School, John Bangma, said his school was in the donation scheme.
That meant it was not allowed to ask for donations or voluntary contributions to school activities, but Bangma said some parents were still happy to make voluntary payments.
"We made it very, very clear that we were not asking, however, we did say that these are the things that parents could contribute towards and we were really impressed with how many parents did pay," he said.
Bangma said the school was still not sure if it was better off in the donation scheme because last year and this year had not been typical years.
The principal of Oropi School near Tauranga, Andrew King, said his high-decile school was ineligible for the donation scheme, but it had still affected the schools' income indirectly.
"It was a mixed bag. It was a small drop across all those sorts of areas, so in terms of a request for a general donation and requests for contributions for camp and what not," he said.
The donation scheme was accompanied by reminders that schools that were not in the scheme could not charge for most activities, but they could only ask for voluntary contributions.
King said that made it more difficult to collect money from families.
"It was a lot harder work in asking families for money and explaining why we needed it," he said.
The principal of Waimea College in Nelson, Scott Haines, said his school last year received less money from donations and voluntary contributions for activities because the pandemic harmed some families' incomes.
He said the rules around charges for school activities also reduced payments.
"All of our large budget lines seem to be dropping. Our international student budget line took an absolute hammering last year and that was our single largest source of discretionary income," he said.
Haines said last year the government provided $20m for schools that lost foreign student income and that money was not available this year.
"So while last year was a tough year for us, I'm very much expecting that 2021 will be real crucible year for schools," he said.