Just 2 per cent of decile 1 students passed the writing component of new standards that from 2024 will be required for NCEA assessments.
Ahead of the nationwide rollout the Ministry of Education has conducted pilots last year and this year.
The report - released on Friday - showed overall just 64 per cent passed the reading standard, 34 per cent writing and 56 per cent numeracy, Te Reo Matatini (Māori language literacy) at 24 per cent and Pāngarau (Māori language numeracy) at just 18 per cent.
But a deeper dive into the data shows the differences between deciles, or socio-economic markets, are stark.
At decile 1, the lowest decile, just 2 per cent passed the writing component - compared to 62 per cent at decile 10, the highest.
In reading the difference between decile 1 and 10 was 24 per cent to 85 per cent, and in numeracy 10 per cent compared to 78 per cent.
The results for decile 2 students had pass rates of just 30 per cent for reading, 12 per cent for numeracy and 8.5 per cent for writing
National Party education spokeswoman Erica Stanford said the results and inequity should be a "national outrage".
"A world-class education system should be judged by how well it lifts children from underprivileged backgrounds and provides them with the opportunity to succeed in life.
"On this measure, Labour is completely failing and has no plan to turn things around."
The new literacy, numeracy, Te Reo Matatini (Māori language literacy), and pāngarau (Māori language numeracy) standards will need to be taken alongside NCEA.
The standards have been developed over years and are being introduced after a 2014 study found 40 per cent of students who got NCEA level 2 and just under 50 per cent level 1 were not functionally literate or numerate.
Ahead of the nationwide rollout the Ministry of Education has conducted pilots last year and this year. A nationwide pilot will also take place in 2023.
Stanford asked Associate Education Minister Jan Tinetti about the results today in the House of Parliament.
Tinetti reiterated the results were from a pilot and the standards and teaching methods were still being developed.
She said the writing, reading and numeracy levels had been falling for "well over a decade" and were why the Government was taking "urgent action".
The Post Primary Teachers' Association (PPTA) has been calling for more time for students and teachers to adapt to the new standards before the rollout began at level 1 in 2024 progressing to level 3 by 2026.