The Post Primary Teachers Association says teachers could refuse to pay fees to their disciplinary and registration body if they lose the right to elect people to it.
The union says teachers pay nearly all of the body's $7 million annual budget and there should be no taxation without representation.
The government is trying to pass legislation that will replace the Teachers' Council with a new organisation, the Education Council, where all members are appointed by the Education Minister.
PPTA president Angela Roberts accepts changes are needed to the Council but it is not right to take away the voice of teachers.
She said she is confused about the changes which seem to be more about control than keeping teachers and children safe.
The PPTA said some teachers are asking why they should continue to pay the council's fees if they lose their right to elect members.
The union says it is offensive that teachers are not trusted to elect people to the new council.