The invoices and documents (withholding tax & general invoices) that you receive from your social secretariat should be processed through fast input and saved as expenses. Strictly speaking, these documents are not invoices but expenses. You can also keep these documents as expense invoices since they don't have a strict numbering. That way you can maintain a complete financial overview.
If you want to visualize an overview per employee, we recommend creating a supplier for each employee. Process the payslips as if they were purchase invoices and link them to the correct employee/supplier. In the employee’s record, store the correct IBAN and BIC code. This way, you can easily pay the salaries together using automatically payment files.