Secretary for Education Lesley Longstone has admitted she would introduce the Novopay school payroll system in a different way if she had a second chance.
"If I were to do it again, I would probably do it completely and totally differently," she told the Parliament's education and science select committee yesterday.
The problematic Novopay school payroll system will be independently reviewed after errors in paying school staff.
Talent2 and the Ministry of Education introduced the system in August.
Asked by opposition MPs why Novopay did not go through a trial before it went into use, Ms Longstone said the system was one of the most complex in Australasia.
"Trialling it in some schools would have been practically impossible, because of the fact so many teachers work in a multiple number of schools and move during the year between one school and another."
She said software that input payroll information had problems.
"The bit of the system that produces the reports back out to schools had had bugs as well - where we've had real difficulties is with the two user interfaces at the input and output side."
Ms Longstone also blamed staff collective agreements for some of the problems.
She said staff were paid under 13 different agreements, and there were up to 10,000 different pay combinations for staff.