There are concerns that thousands of students at low decile schools are missing out on support that could help them ace their exams.
The qualifications authority, NZQA, reported just 3 percent of students sitting exams at decile 1 schools were using Special Assessment Conditions (SACs).
These would provide students with, for example, an assistant to read exam questions, or to write down their answers should they struggle to do it themselves.
The number of students accessing SACs at decile 10 schools was four times higher at 12 percent.
The Dyslexia Foundation said this meant there were thousands of students across the country not getting the exam help they needed.
Mele Sateki was a student at decile 1 Papakura High School in south Auckland. She had been using a reader in her exams since Year 9 when she moved to New Zealand from Tonga.
It helped her process her ideas and overcome the language barrier, she said.
"I feel like sometimes I struggle a lot, so having someone by my side helping me with reading and trying to understand, because there are some... words that people are using in the exams, and some of them I don't understand."
Using exam assistance was helping her reach her full potential, Mele said.
"I feel like if I do it by myself I'm gonna be alright, but having someone there, helping me with all that makes my mark a bit higher."
Papakura High School had higher rates of exam assistance than other decile 1 schools, with nearly 8 percent of their NCEA students using it. But principal Simon Craggs said there were still some barriers to accessing SACs.
The main issue was the cost of getting a diagnosis for a learning difficulty.
"There needs to be funding available for students to get official diagnoses."
Schools were able to apply for exam help for students who did not have a diagnosis, but Craggs said the process was time-consuming and difficult to navigate.
It could also be difficult finding enough staff to help students with their exams, but Craggs said the improvements it results in make it all worthwhile.
"Having SACs for a student who does have difficulty in putting their ideas on paper is life-changing."
Dyslexia Foundation chairperson Guy Pope-Mayell said it was important to understand SACs were not about giving anyone an unfair advantage.
"For somebody who's got a learning difference, they're not being advantaged, we're simply levelling the playing field."
While the overall number of students using SACs had increased in the last 10 years, the decile gap refused to budge.
Lower decile students might also feel stigmatised for their learning difficulties, and may be reluctant to ask for help with their exams, Pope-Mayell said.
"There can be student stigma, there can be parental stigma and there can be general stigma related to that particular issue."
He called on the Ministry of Education to set aside funding for lower decile schools to access SACs so those that need it didn't miss out.