by Maggie Taggart
BBC NI education correspondent
Thousands of pupils in Northern Ireland will get some GCSE results later but results from exams taken with English and Welsh boards are due on Thursday.
Schools have complained that the late arrival of grades is "a nightmare" for decision making and paperwork.
They will only have a few days between finding out the grades and having to accept or reject pupils who want to study for their A levels.
Two thirds of GCSEs in NI are set and marked by the local board, the CCEA.
However, that still leaves a third with English and Welsh boards.
The results dates change, but this year's date is just about the latest possible.
CCEA will release its grades on Tuesday, but the rest will not be revealed until Thursday.
The results are particularly important for pupils who want to study A levels, either at their own school or a different one.
Some schools are reopening this week and say the lateness makes decision-making and paperwork very difficult.
There will only be a few days between finding out the grades and having to accept or reject pupils.
School uniform suppliers say some parents have taken a chance and booked new blazers, skirts and trousers in the hope their children will get good enough results to continue to A levels.
The full statistics of the results will not be known until Thursday.
The exam boards have now agreed to bring forward next year's results by two days and to publish them all on 24 August 2010.