Fewer students are attending school regularly as figures reveal "patterns of absences".
And the Government is warning parents to take their child's school attendance more seriously.
Data taken from Term 2 last year showed there was a drop in the number of students going to school regularly, while Mondays and Fridays were the most frequently skipped days.
And 22 per cent of students weren't present on the last day of term.
Associate Education Minister Tracey Martin said parents needed to take school absences seriously.
"Education really matters and we all have to take attendance seriously.
"Going to school is what sets our young people up for life."
The data, released this afternoon, showed while most of the absences were justified - for example if a child was sick - there were some increases in unjustified absences.
The average attendance rate was 88.6 per cent last year while "regular attendance" is measured as a student being at school 90 per cent of class time.
Research showed that every day away from school could affect results, Martin said.
For example, students attending 95 per cent of days in Year 10 later get an average of 75 credits at Level 3, which was plenty to achieve the qualification.
But of Year 10s who attend 85 per cent of the time, only about half go on to achieve NCEA Level 3, Martin said.
The downwards trend in attendance had been going on for a few years - except for 2018 - and it had to stop in order young people got the education they needed, Martin said.
It was justified if a child needed to stay home because they're ill and most of the absences recorded in the data were because of this, Martin said.
The minister acknowledged this "is a tricky thing to talk about at the moment with the fears around the coronavirus".
"But it is clear from the patterns of absences – they are worse on Mondays and Fridays, and 22 per cent of students weren't at school on the last day of term – that something else is going on."