The EU legislation does not specify how to calculate the average number of employees for categorizing undertakings under the Accounting Directive. However, Member States may have national rules or guidance on this. In the absence of such guidance, companies can refer to the 2003 Commission Recommendation, which defines employee headcount, based on annual work units (AWU). This includes full-time employees, part-time and seasonal workers as fractions of AWU, and excludes apprentices or students in vocational training, as well as periods of maternity or parental leave.