School principals say the NCEA is too much work for teachers and the problem could prompt more schools to adopt alternative qualifications.
The Secondary Principals Association says teachers like the NCEA but the workload associated with the qualification is demoralising and undermines it
The Secondary Principals Council, which is part of the Post Primary Teachers Association, says current work aligning the NCEA with the curriculum is particularly demanding.
Both groups say the high workload could push more schools towards other qualifications, such as the Cambridge International Exams, which require less work by teachers.
The Qualifications Authority has a working group looking at the problem and expects it to make recommendations by the end of the month.