SIRET number.

[Michael1783]

I contacted an online company in France to help me submit my tax return online for my Airbnb income from my apartment in Nice. 

I paid them €299 but I then had an email to say that they wanted another €480 to get me a 'SIRET' number and they would not be able to submit my return without it. 

They did not mention this during my enquires. 

Does anyone know if I need a 'SIRET' number?

It is not a business as such in that I only let it out when I am not using it myself. 

My profit last year was only about €1500

If I do need one is there a cheaper way that I can get one?

I look forward to your advice. 

Michael