The National Association of Principals and Deputy Principals (NAPD) is warning schools that parents do not have an automatic right to information - once their child turns 18.
The warning comes after the organisation sought legal advice on the Data Protection act.
The NAPD says it is becoming more of an issue now than previously - because of the aging population of our school attendees.
NAPD Director Clive Byrne says pupils over 18 must be written to directly.
Speaking to Newstalk Breakfast, Clive explained, "that is the law. An 18-year-old is an adult.
"Under the data protection legislation and under the Education Act, 18-year-olds have a right... to be corresponded with in matters to do with reports, complaint & grievance procedures and so on," he added.
He also explained that there are more pupils over 18 in the final year of secondary school than before, due to the number of students doing transition year and as a result of many children starting school at the age of five rather than four.
