Mr Kahukiwa said the first he knew of any issues was three days into his next placement, at Tikipunga High School in May. Once the school found out he was from a charter school, the board asked him not to return.
"I was just astounded," he said. "I had no idea why or what was going on. I'm just one teacher trying to do what [the PPTA members] all joined for, which is educate kids, uplift the kids and share my skills."
PPTA president Angela Roberts said, while the boycott was by definition discriminatory, it was legally and ethically sound.
"After opposing the charter school policy all the way through the legislative process, PPTA members decided that it would be consistent and principled to continue this opposition when charter schools are established," Ms Roberts said.
Charter schools should not be propped up by the goodwill and expertise of teachers in the state sector, she said. It was "highly hypocritical" of them then to seek assistance from qualified teachers in the public system.
Last month Education Minister Hekia Parata told the Northern Advocate: "I think it's utterly disgraceful that the PPTA is preventing the teacher getting a placement in a school."