More than a third of children failed to attend school regularly last year and girls in Year 13 were the worst offenders.
The Ministry of Education's annual attendance survey in term 2 last year found 63.8 percent of students were regular attenders, meaning they missed fewer than five days of the ten-week term.
It said the figure was short of the ministry's goal of 70 percent but better than the low of 63 percent recorded in 2017.
Six percent of children were chronically absent in term two last year, missing at least 15 days of term two.
"Repeated across the year these students are likely to miss over three months of learning. Essentially, they will lose at least a term," the report warned.
It said only 42 percent of Year 13 girls attended school regularly in term 2, the worst figure for any group of students and compared to 47 percent for Year 13 boys.
Carterton district and Ōrākei in Auckland had the highest rates of regular attendance at 75 percent, while the worst was in Kawerau with just 38 percent.
The report said a small improvement in attendance by some students would change the overall figure significantly.
It said encouraging students with regular absence to attend five additional half days could see term 2 attendance rise up to 79.1 percent.
The report showed Asian students had the highest rate of regular attendance, 75 percent, while Māori students had the lowest at 50 percent.
It said 47 percent of students in decile 1 schools were regular attenders last year, while in decile ten schools the figure was 73 percent.