This Practice Note discusses the management of employee underperformance in Ireland. It covers informal performance management, performance improvement plans (PIPs), documentation and escalation, with reference to the Unfair Dismissals Acts 1977–2015 (Ireland) (as amended, UDA 1977 (IRL)), the SI No 146/2000 Code of Practice on Grievance and Disciplinary Procedures (Declaration) Order 2000 (Ireland) (SI 146/2000 (IRL)) and the Employment Equality Acts 1998–2015 (Ireland) (as amended, EEA 1998 (IRL)). It also covers data protection considerations under the General Data Protection Regulation, Regulation (EU) 2016/679 (EU GDPR) and probation limits under the SI No 686/2022 European Union (Transparent and Predictable Working Conditions) Regulations 2022 (Ireland) (SI 686/2022 (IRL)). Under UDA 1977 (IRL), lack of competence is a potentially fair reason for dismissal, that is, if the standard of performance was clear and the employee had a fair chance to meet it. Optimally, employers should start performance management with clear role profiles and measurable key performance indicators (KPIs) to safeguard against claims. Foundations SI 146/2000 (IRL), made under the Industrial Relations Act 1990 (Ireland), is used