Some A-level resits are to be scrapped under changes being introduced by Northern Ireland Education Minister John O'Dowd.
New students from September will not have the opportunity to retake tests in January. The change does not affect pupils already embarked on A-level study and there will also be one resit in June each year.
The National Union of Students said removal of the resit was a "retrograde" step.
Mr O'Dowd said he was keeping the modular system of exams in place, with assessments of each unit, rather than all exams being held at the end.
"Following that consultation and associated events I have made a decision on A-level policy that I am convinced is in the best interests of learners here and will ensure the integrity of our A levels," he said.
The changes will come into effect in September. They follow a separate review in England which proposed more extensive adjustments to the A-level system with the AS-level being a standalone qualification.
Mr O'Dowd has asked the Council for the Curriculum, Examinations and Assessment (CCEA) to consider a change to the weighting of AS/A2 parts of the course from 50:50 to 40:60.
He added: "I believe these decisions will ensure that our A-level qualifications remain equitable, robust and portable and are credible in the eyes of higher education institutions and employers. They fully protect the interests of all learners and give them every opportunity to progress in their chosen career path."
National Union of Students-University Students of Ireland (NUS-USI) president Adrianne Peltz said the announcement must ensure clarity for students and must maintain the integrity and transferability of qualifications. She claimed removing the January resit option for new A-Level students and potential change to the AS/A2 weightings were retrograde steps.
"I am extremely concerned that the removal of the January resit option for new A-Level students could disadvantage students and provide them with less opportunities to reach their potential," she added. "I am also worried that the potential change of weighting as regards AS/A2 qualifications could undermine AS levels."