Relief teachers who are members of the ASTI say they are finding themselves impacted because of the union's opposition to the new Junior Cert cycle.
Members of the Association of Secondary Teachers in Ireland (ASTI) are barred from taking part in training for the new programme.
However, secondary teachers attached to the Teachers Union of Ireland do participate.
Noel Hogan, a temp teacher currently teaching History and Geography at St Louis Secondary school in Carrickmacross, Co. Monaghan, thinks it will have a direct effect on his career prospects.
Mr Hogan said: "If I go for work from this summer on, because of these directives I am going to be disadvantaged when it comes to interview.
"If you were a principal, and you had a choice between me who can't do the training because of the directives, or a TUI member who can, who would you employ?"