The Department of Education, Sport and Culture says it doesn't know how much supply teachers cost over the last five years.
A Freedom of Information request asked for the cost of supply teachers for primary and secondary schools.
The education department said supply teachers were paid between £28.52 an hour and £36.45 an hour,.
But it said it didn't have a total amount spent on supply teachers, and suggested the Cabinet Office might have the figure.
MHK wants changes to tax laws for couples
What does it take to close roads?
Firefighters called to fire at tip this morning
Airport recruiting for firefighters
Northern roads to close for half marathon this weekend
City centre street to close for two days
Workshop about impact of substance abuse this morning
Total of 44 bus services running during strike today