It is taking nearly a month longer to re-engage students disconnected from the school system since Labour came into power in 2017 - one requiring a massive 1914 days.
The number of students affected is rising.
While the pandemic and difficulties for Attendance Services to make home visits have played a role, the trends began before the onset of Covid-19, and have continued despite increases in funding.
It comes as the Government is set to announce a package to tackle stubbornly high truancy levels, with now over 40 per cent of students not going to school regularly - an increase of 10 percentage points since 2015, with huge disparities for Māori and Pacific children and lower-income households.
With school attendance one of the five key indicators of child poverty, National says at an average now of nearly four months to re-engage non-enrolled students the Government's inaction is hurting the future prospects of thousands of children.
Associate Education Minister Jan Tinetti told the Herald she accepted the trends had worsened under Labour, but the former principal herself said it could be linked back to structural changes to the monitoring system in 2013.
"In 2013 - I was a principal at the time - Attendance Services changed structurally. It used to be quite close to schools but became more centrally located, more bureaucratic and has taken away that local response."
Tinetti said problems had grown since then, with regular attendance declining and re-engagement times increasing as a result.
The Herald understands a pre-Budget announcement will canvass these issues.
Education data released to National showed since 2017 the average number of days it took to re-engage non-enrolled students increased from 85.6 to 113.9 last year.
It also showed the 20 longest times had all increased substantially since 2015, the peak year for regular attendance over the past decade, from 741 days to 1914 days in 2021.
There had been a steady increase in non-enrolled students since 2015, from 7223 to 9076 in 2017 and 10141 in 2021 (this was a small decrease from 2020, largely affected by lockdowns).
It comes as the latest data for regular attendance, for term 2 last year, remains about 60 per cent - a 10 percentage point drop from 2015, and similar to 2019.
Ministry of Education research shows each additional half-day of absence is associated with a reduction in the number of NCEA credits students subsequently attain.
National's child poverty reduction spokeswoman, Louise Upston, said the Government was failing the most vulnerable children.
"Every day of missed school harms a child's academic outcomes and wellbeing. The fact it now takes almost four months to re-engage children at school is hurting their future prospects."
Upston said schools should be required to report complete attendance data, and more frequently.
"This will enable challenges to be identified sooner, and the efforts to re-connect students with education to start sooner."
Covid-19 restrictions were "not a valid excuse" and, given its link to poverty, re-engaging these children should have been made an essential service, she said.
It came after the Herald revealed Government-funded truancy services were so poorly resourced more than 30,000 students who missed at least three days of school a fortnight were out of reach.
Those service providers contracted by the Ministry of Education received about $9.7 million annually, enough to reach about 22,000 students. Budget 2021 allocated a further $21m over four years covering an extra 7500 students.
The inquiry found steadily declining regular attendance rates - attending 90 per cent of the time by half days - since 2015, from 69.5 per cent to 59.7 per cent in 2021 for term 2 of each year.
The inquiry found attendance levels for New Zealand students far lower than in Australia, Canada, Ireland, the United Kingdom, and the United States.
A 2018 international survey found 29 per cent of students here reported skipping school on at least one day, compared with the OECD average of 21 per cent.
In Aotearoa, Māori and Pacific children saw the greatest declines in regular attendance since 2015, of 12.3 and 15.8 per cent respectively, versus 10 per cent for Pākehā and 7.7 per cent for Asian students.
In term 2 of 2021, 44.4 per cent of Māori and 44.8 per cent of Pacific students attended school regularly.
While there were declines across all deciles, regular attendance among the poorest students, decile one, declined nearly 17 percentage points since 2015 to 40.9 per cent, while those in decile 10 dropped just over five points to 71.7 per cent.
There had also been a steady increase in students chronically absent (attending 70 per cent or less of available school days) from 4.6 per cent in 2015 to a peak of 8.7 per cent in 2020, and down to 7.7 per cent last year.
Tinetti said the Government would be responding to that inquiry's report in the next few weeks and revealing a strategy to address the issues.
"I am aiming for something that is more locally responsive, with local solutions to the issues.
"I've always maintained local schools, local services and NGOs working together is how we are able to best engage and get these children back in the classroom."
Tinetti said she had been through a similar experience herself as a principal working in Invercargill about 15 years ago, when through a community approach schools were able to turn around some of the worst attendance rates in the country.
Tinetti said the inquiry had revealed a whole range of issues, along with policies that had helped keep children at school, such as the free lunches programme, period products in schools and alternative forms of education, as highlighted through at-home learning.
"We can talk about attendance and bums on seats but really it is about education and engagement.
"I don't want to put a figure on that yet, it's too linear, but we want to see all young people engaged in learning as soon as possible as every one not learning is a lost opportunity."