The inequalities between the country's richest and poorest state schools has been revealed in data released by the Education Ministry, says the Post Primary Teachers Association (PPTA).
Ministry of Education data provided to RNZ News showed about 81,000 primary and secondary pupils - 11 percent of the total school population - are attending schools they are not zoned for.
The figures show that dozens of schools are taking more than half their pupils from areas that did not fall within the school's zone.
PPTA president Angela Roberts said zoning was meant to stop more well-off parents from shopping around for the best school, but that was not happening, with lower decile schools suffering the effects.
"The school is left with the students who are probably more vunerable. That doesn't mean these kids don't have great opportunities in life, but you don't have that good mixture of students, like we end up with in society. You can see there are vast differences between our wealthiest state schools and our poorer.
She said some schools had far greater access to outside funding while others struggled to get by, and students who were more mobile and less vulnerable tended not to attend their local school if it was not well-resourced.
"The Ministry's very comfortable with the way things are. What they need to do is show greater leadership in the management of the schooling network. Some schools are bulging at the seams, others can't fill their classrooms, and that seems a very inefficient and ineffetcive use of taxpayer funds. It would be great if every school was resourced so the lcoal school was the first choice."
Senior Ministry official Katrina Casey said it had confidence in enrolment schemes and the vast majority of families abided by the rules.