The Education Minister Richard Bruton is hoping teachers on a career break might agree to sub in order to deal with the shortage of part-time teachers.
Principals say they are finding it increasingly difficult to find substitute teachers.
Minister Bruton said it was partly a result of creating more full-time teaching posts in the past few years.
He also said they are employing a number of ways to deal with the shortage.
Mr Bruton explained: "We have encouraged people who are retired teachers to remain on the register so that they can take up those vacancies.
"In addition we are providing that teachers who are on a career break, and they can be on a career break for up to five years, that they could work up to 90 days in a year and not transgress the rules of their career break.
"So we are looking at ways in which you could meet what are short-term needs."