The Cook Islands Ministry of Education says pass rates for NCEA Level One students are set to improve now that all credits have been included.
To pass NCEA Level One, students must gain 8 literacy credits in either English or Cook Islands Maori.
However, last week the New Zealand Qualifications Authority confirmed that Cook Islands Maori credits were erroneously omitted.
12 students have been affected but NZQA has now amended students results to ensure all credits have been included.
The Education Ministry says the initial interim percentage pass rates were lower than expected at Level One but with the inclusion of the missing results it is confident the pass rates will improve significantly.
It says it is not aware of any students for whom this has impacted on their subject choices.
The final analysis of NCEA results will be conducted around March.