The relation between employer and employee is a special one as there are many legal provisions that protect the position of the employee in particular. You may vary some provisions (in writing), but this is not possible for many of them. For example you may think you can simply terminate a contract of employment, but then have to walk the expensive path of permission to terminate employment or dissolution by the cantonal court.

Even worse: someone who works for you on an invoice basis may be regarded as an employee.

We can give you answers to your important questions such as: What are the contractual consequences of flexible labour? Why is there a need for performance reviews with employees?

Can people send you an invoice for their work?