Hi I've been living and working in Luxembourg for a while now, but now I want to know if I can declare a few swimming lessons I teach during the weekend? They are private swimming lessons. I'm qualified, but the swimming lessons are not officially set, just agreed on by email. Does anyone know how I need to declare this? And what do I need for this, when i declare it? Do I need a certificate? Because I cannot hire a lane in the swimming pool, so I need to find out if there's anything else I need, before declaring myself actually.