The activities referred to in Article L. 8221-3 are presumed, in the absence of proof to the contrary, to be carried out on a profit-making basis:
1° Either when they are carried out with recourse to advertising in any form whatsoever with a view to seeking customers;
2° or when their frequency or importance is established;
3° Or when invoicing is absent or fraudulent;
4° Or when, in the case of craft activities, they are carried out using equipment or tools that, by their nature or size, are of a professional nature.