The bulk of decile funding comes under the banner of Targeted Funding for Educational Achievement (TFEA). Decile one schools receive a maximum of $905.81 per student, while decile 10 schools receive no TFEA funding.
The initial decile five rating was inaccurate, Golden Sands School principal Mel Taylor said, but the decile jump has meant the primary school has increased its annual student donation by $20 a year to cover costs, and regularly applies for funding from external bodies.
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"We have never got enough money to do what we try to do - that's very common. We try to get contributions both in time and donations from parents, but our parents are working parents so time is hard to get," said Ms Taylor. "Just because you've got a high decile school doesn't mean the community is able to contribute; that's an assumption."
Deciles are re-calculated after the census every five years. But, with the 2011 census being delayed by two years after the Christchurch earthquake, schools who felt they were under-funded were doing it tough for a long time, according to the chair of the New Zealand Secondary Principals Council Allan Vester.
"I know a lot of schools would complain they've lost money - the other way of looking at it is schools that have gone down in decile really should have had the additional money earlier. If you were one of these schools, there would be a number of years where you were under-funded according to the real decile," said Mr Vester.
"In the seven years between censuses, you'd get significant social shifts throughout a community."
Mr Vester said funding drops almost never affected the number of teaching staff, but often hit administration staff and extracurricular activities.
Education Minister Hekia Parata has called the decile system complicated and clumsy, and is looking at how school funding can be improved. She said a review is in its very early stages, and any decisions are "still some way off".