This is the first time we ask for help with cleaning from an external person.
I have a recommendation, but he doesn't speak English well enough for me to ask if he's doing his taxes himself (being Spanish, he's just gonna say "yes yes" on everything he doesn't understand

).
The monthly amount is not much (300CHF) but I'd rather err on the safe side with the paperwork.
Do I need to be worried if he just takes the cash and won't register his own company to account for the income?
Do I owe any social insurance bits after his fees to anyone? Do I need to register him working for us?
Can I assume he's going to tax his income properly and pay his own dues?
Do I need an official (paper based) contract with him?
Do we need to exchange (or keep) any sort of paper receipts for any reason?
First and foremost I don't want any trouble with the law. Second, I'd like that he also does it the most legal way, but for that end I obviously don't have any influence.