hey !  probably too late but....

charging for online advertising is like charging for anything... it will completely depend on the buyer - i.e. does he need an invoice ?

if the buyer needs a real invoice, then you'll have to emit one. If this invoice is from Swiss Territory, for it to be official, it has to come from a registered company (even if it is a sole property *raison individuelle*). That's easy to do. If the invoice comes from your personal name, you would need to be registered as *independant* at the Caisse Cantonale de Compensation for it to be perfectly official. And in any case, you'd have to report all that to AVS and taxes.

Other way, is forget all that, get your guys to pay through PayPal, and when you're making loads of big bucks you'll get that settled ;)

 Hope that helps!