The requirement to dedicate at least 50% of the working time to the action for both professional and personal reasons was outlined in the MSCA H2020 Work Programme 2018-2020 on p.95 “In cases of part-time work, all researchers must dedicate at least 50% of their working time to the MSCA action, whether they are working part-time for family or other reasons”. When it comes to parental leave, it falls under personal or family reasons. However, the fellow would still have to dedicate at least 50% of the working time to the project.