Belgium has published Circular 2023/C/49 of 27 April 2023, which concerns the 80% payroll withholding tax exemption for qualifying R&D personnel. In particular, the Circular addresses the registration of an R&D project or program, which is one of the conditions for the exemption. With effect from 1 August 2023, R&D projects or programs must be registered with the Federal Public Pla…