The postponement follows three separate pilot years but the Department of Education is no nearer agreement on a workable system.
Education minister Michael Ancram confirmed he has still to decide what form the assessment will take, although he insisted the maximum benefit had been derived from the pilot years.
The NASUWT, the largest teachers union in the province, is to maintain its boycott of assessment in the province in spite of the new delay.
Regional official Tom McKee said it had urged Mr Ancram to make the same concessions on the issue as in England and Wales. So far Mr Ancram has failed to introduce external marking or reduce the statements of attainment.
The minister blamed changes to the common curriculum for the decision to put off statutory assessment until the 199697 academic year. "It would seem rather perverse to attempt to introduce in 199596 a statutory system while a major review of the curriculum is underway," he told a headteachers conference on Tuesday.
"Teachers will, moreover, want to be devoting their efforts in 199596 to their preparation for teaching for the following September."
The decision means the province will be four years behind the mainland on the introduction of assessment but Mr Ancram said it will become statutory at all key stages in the 199697 school year.
The form assessment will take is a complex issue, but the options available would be teacher assessment, tests only, or a combination of teacher assessment and external tests. Mr Ancram stressed no decision would be taken until he had heard the views of teachers, and he has asked the Council for the Curriculum, Examinations and Assessment to conduct a full consultation with teachers.
He said the consultations could not avoid the thorny problem of the link between assessment at key stage 2 and the controversial 11-plus transfer of pupils.