I understand that there is no net saving involved in using newly qualified teachers for substitution work rather than retired teachers. Both newly qualified teachers and retired teachers who return to work in a substitute capacity are paid the same rate of pay for substitute work.
The salary scales and the substitution payment rates applicable to qualified and unqualified teachers are set out in Departmental Circular 51/2018. This Circular is available on my Department’s website at https://www.education.ie/en/Circulars-and-Forms/Active-Circulars/cl0022_2019.pdf
Circular 31/2011 issued by my Department requires school management authorities to give priority to qualified registered teachers rather than retired teachers in relation to substitution work.