Tax on subletting

Hi everyone,

Has anybody ever had experience on declaration of income from a foreign property which is not owned rather sub-let (I am renting an apartment outside EU with my girlfriend who is living there, and we are sub-renting it on Airbnb to pay back at least expenses and keeping it for when I will be back; profit from it is really small, below 2000chf per year probably)?

Does it need to be declared?

Are there any special points to care of?

Thank you.

p.s. 'income' is received in an EU bank account and always sent back to pay for rent, small housejobs, as well as furnitures and my girlfriend to afford living