Solution : https://service.sap.com/sap/support/notes/1000958 (SAP Service marketplace login required)
Key words : 
payroll -> payroll switzerland -> tax -> wage statement 2005 -> customer enhancements, payroll switzerland, hrpaychlaw2b badi, implementation guide, note 942060
Related Notes : 
       
| 942060 | LAW 2005: BADI for comments on part-time employment |