Under the Education Welfare Act 2000 parents must inform the school if their children will be absent from school on a school day and the reason for the absence, such as illness. It is best to do this in writing. The Child and Family Agency strongly advises against taking children out of school to go on holiday during term-time.

Parents and guardians have a legal obligation to ensure that their child attends a school or else receives an education. If Tusla considers that a parent is failing in his or her obligation, it must send the parent a School Attendance Notice. The warning outlines that legal action will follow if the child does not attend school regularly. Tusla must make reasonable efforts to consult with the parents and the child, before sending the warning.

If the parent fails to comply with a warning, they may be prosecuted. If convicted, the parent may be fined and/or imprisoned for a month and also fined for each subsequent day that they fail to send the child to school. If the parent claims that suitable alternative education is being provided, they must prove this. It will be a defence for the parents to show that they have made all reasonable efforts to send the child to school – in such cases, the Child and Family Agency must be informed.

Tusla has a leaflet for parents Don’t let your child miss out.

From citizensinformation.ie

How Parents Can Help Make Every School Day Count

• Establish a good routine in the mornings and evenings so your child is prepared for the school day ahead.
• Make sure your child goes to school regularly and follows the school rules.
• Ensure your child arrives at school on time – not late.
• Arrange dental and medical appointments outside school hours when possible.
• Always inform the school if your child is absent due to illness – this should be followed up with a written note when your child returns to school.
• Take truancy seriously – if your child is not attending school as you expect they may be putting themselves at risk – Who are they with? What are they doing?
• Take family holidays outside term.
• Talk to your child about school and take an interest in their school work (including homework).
• Attend parent evenings and school events.
• Praise and reward your child’s achievements at school.
• Always support school staff in their efforts to control difficult or challenging behaviour.
• Discuss any problems or difficulties with the school – staff are there to help and will be supportive.
  
  From https://www.tusla.ie/every-school-day-counts/