Sick leave is time where an employee would normally be working but they are unable to do so due to some sickness or injury which is keeping them out of work. Important considerations around sick leave include that if an employee is certified sick at a time when they are on annual leave then that counts as sick leave and those days may be re-taken as annual leave at a later date. Similarly, where an employee has been out sick for an extended period of time then they are still entitled to their public holiday entitlements where the public holiday falls within the first 26 weeks of such sick leave; this is extended to 52 weeks in cases of occupational sickness or injury.

Currently in Ireland an employee who works in the private sector is not entitled to accrue annual leave while on sick leave. As a result of a European Court of Justice ruling, employees in the public sector are, however, entitled to accrue annual leave on sick leave. It is envisaged that in the future the Organisation of Working Time Act 1997 will be amended such that private sector employees will then be entitled to accrue annual leave while out on sick leave.