Schools are entitled to set aside up to 30 minutes of the school day for religious instruction, twice the amount of time devoted to subjects such as physical education.
However, time spent on religious instruction normally increases when faith-based schools become involved in preparing children for sacraments such as Holy Communion and Confirmation.
If the Archdiocese of Dublin ends up reducing or removing sacramental preparation from the school day, it could result in an "opt-in" system of Communion or Confirmation.
This type of system currently operates in multi-denominational schools, such as Educate Together or Community National Schools.
It typically involves a weekly one-hour after-school class either in the school or the local parish centre.
Classes are usually taken by a religious teacher, lay person or local priest and generally involve a cost for the parent.
Paul Rowe, chief executive of Educate Together, says up to 50 per cent of children who attend its schools self-identify as Catholic and attend such faith formation classes outside schools hours.
He says the feedback he has received from members of the clergy is that it is leading to greater engagement in the parish and stronger faith formation.
Some parishes have also introduced programmes aimed at boosting parental involvement around the sacraments.
Do This In Memory Of Me is a programme where parents are invited to attend mass regularly with their children, with special masses held on a monthly basis over a nine-month period in the lead-up to Communion.
Some teachers say these programmes are helping parents and children prepare which, in turn, means there is less time taken from academic tuition for sacramental preparation.