Twenty-five post-primary schools are to get extra places for new pupils in 2020.
The Department of Education (DE) has created 443 additional places to cope with an expected increase in demand in some areas.
Twenty schools have also been given 361 extra places in expectation of increased pupil numbers in 2021.
The department had previously warned of pressures on post-primary places in 2020 and 2021.
As a result they had asked principals to apply for temporary increases in their pupil intake for those years.
In 2019, 226 pupils had not got a post-primary place when the initial transfer process concluded in June and there was concern that number could rise this year.
The number of pupils due to transfer in 2020 is 24,017, compared to 21,732 in 2017 - a rise of more than 10%.
Those figures do not include pupils with statements of special educational needs, who are placed through a different process.
'Focus on welfare of children'
The department has now decided that a number of post-primaries in Belfast, north Down, Strangford, Newry and Armagh, Fermanagh and south Tyrone, south Antrim and mid-Ulster will get extra places.
In Belfast Grosvenor Grammar, Ashfield Boys' and Girls' High schools, Strathearn College, Our Lady and St Patrick's Knock, St Malachy's College, Dominican College and Blessed Trinity College will admit between 10 and 30 more pupils in 2020.
In addition, Aquinas Grammar will admit 20 extra pupils in 2021, though none in 2020.
St Patrick's College in Dungannon will get 22 extra places in both 2020 and 2021 while the nearby St Patrick's Academy will admit 15 more pupils than normal in those years.
In Magherafelt, St Pius X College is to admit 30 extra pupils in both years while St Mary's Grammar is to admit 12 additional pupils.
Antrim Grammar will get 24 extra places in 2020 and 2021.
In Newry, St Colman's College will take 15 more pupils and Our Lady's Grammar will admit 28 more in 2020 and 2021.
St Paul's Bessbrook will take 30 additional pupils into year 8 in both years.
In north Down and Strangford, Bangor Academy, Bangor Grammar, St Columbanus College, Regent House, Saintfield High, Movilla High, Nendrum College, Glastry College and Strangford Integrated will all admit some extra pupils in 2020.
Five of those schools, mainly in Bangor, will admit extra pupils again in 2021.
Education Minister Peter Weir said his department had carried out a detailed analysis of where demand was greatest.
"In light of this, I have moved to provide additional Year 8 places in areas where pressure is expected to be highest and have authorised an additional 443 places in 2020 and 361 places in 2021," he said.
"My focus is on the welfare of children and to minimise stress on families at transition and I may authorise further increases during the admissions process if they are required."
A number of schools have already sought permanent increases in enrolments which is a separate process.
Schools will still be able to apply for future temporary increases in their pupil numbers should admission pressures arise later in the transfer process.
Parents applied for post-primary places for their children in January 2020 and will find out which school their child has been given a place in on 30 May 2020.