It also does not separately identify numbers of teacher trainees who will graduate in the next few years. Domestic students starting primary or secondary teacher training dropped by 39 per cent from 4445 in 2010 to 2725 in 2016, before recovering slightly to 2785 last year.
Instead, the projections assume that the numbers of teachers entering and leaving the profession at each age level will follow the same trends as in recent years and then level off.
The shortfalls for secondary teachers in future years arise from growth in student numbers. A small bump in the birth rate between 2007 and 2012 has pushed up primary school rolls in the past few years, but primary rolls are expected to dip slightly and secondary rolls will rise as these children move into high school from about 2020.
The result is a projected shift in primary schools nationally from a shortage of 650 teachers next year to a surplus of 90 teachers by 2023, before recent immigration growth feeds through into shortages of 70 primary teachers in 2024 and 230 in 2025.
Meanwhile the model projects a continued widening of the shortfall for secondary teachers from 170 next year to 1750 in 2023 and 2210 in 2025.
In Auckland, higher population growth will see even primary schools remain short of teachers throughout the period, widening from a low point of 60 in 2023 to 350 two years later.
The shortfall in Auckland secondary schools will widen from 130 next year to 680 in 2023 and 860 by the end of the period.
The ministry's deputy secretary for evidence, data and knowledge, Dr Craig Jones, said the model was reliable only for the next two years, but would be affected by unpredictable policy changes and economic conditions in later years.
Its deputy secretary for early learning and student achievement, Ellen MacGregor-Reid, said the ministry would try to close the gaps by lifting numbers of trainees, former teachers returning to the profession, Kiwi teachers returning from overseas and foreign teachers recruited from overseas.
"In the last few weeks, as a result of the publicity, one of our recruiters has had more than 1000 expressions of interest in coming into New Zealand from returning teachers or other qualified teachers," she said.
"We are looking at teacher training settings. We have seen very successful teacher training options, such as TeachFirst NZ that sees teachers working while they are training.
"We are currently looking at what more could be adjusted in teacher training to make sure it is attractive and a great start.
"We are looking at teacher workload. That has been identified as an issue by the sector."
But she said the ministry was not concerned that training providers such as Auckland University were cutting staff because of the fall in trainee numbers.
"Universities make a range of decisions about how they run their businesses," she said.
"My understanding is that teacher training is still operating at strong levels. At the moment we are not concerned about that."
Post Primary Teachers Association president Jack Boyle said the projections were flawed because they assumed that teacher supply and demand figures for 2017 were equal.
"Instead of quantifying the shortage, the Ministry of Education has done its sums under the assumption that there were the correct number of secondary teachers in 2017," he said. "Secondary teachers know this is not correct."
