Just like every citizen of the Netherlands, your employee will need to be registered at the city hall. This is important in many ways; such as obtaining a BSN (fiscal number) and also Immigration related issues.
In most cases there is also a possibility in the tax department to get a special facility. This facility is known as the “30%-ruling” and can be applied for and approved under certain requirements. This ruling is very profitable for the employee in their finances. The actual benefit in this ruling is getting 30% of the gross income tax free!