I am living in Denmark (and a Danish citizen) and I am going to host a friend from Argentina for a month. Argentinian citizens require no visa to enter Denmark (or Schengen) as tourists.
I have been calling the Argentinian Embassy and also the Danish Immigration service without an answer to my question, which is:
How do I prove that I am the host and financially responsible for my friend during the stay?
As seen on the official Danish Immigration website:
If you are travelling visa-free, you will normally be permitted to enter Denmark if you fulfil the following general conditions:
You have the necessary means to pay for your stay and return trip. What will be considered as necessary funds depends on the length of your stay and whether you will stay at a hotel or in a privately owned home with family or friends. As a general rule, you must have at your disposal approx. DKK 350 per day. A smaller amount may be accepted if you are staying in a privately owned home and your host will cover all the costs. If you are staying at a hotel, you must have a greater amount at your disposal, approx. DKK 500 per day.
How does my friend prove that he is staying with me and I will cover the costs? In Spain there is an official "Invitations letter" that you can go and get stamped at the police station, and that will be proof enough. However, in Denmark, the only official invitation letter is for Visa Required travelers only, as far as I know.