Since you live there, you obviously have better info than I do,SY. But here is what I have observed. If you are in a small pueblo with a medical attention place staffed by doctors, they are unlikely to have any way to generate a bill. For instance, a couple of years ago I was in La Robla and needed to get a tick bite looked at. The small office there had a doctor and a nurse, but nothing that would enable them to write up a bill and charge me. I suppose they could have declined to treat me, but I would be surprised if that happened. In a city with a large clinic or hospital, though, I know that bills are generated, and in fact sometimes you must pay upfront. This happened to me in a very modern private hospital in Lisbon, but the charge was a small fraction of what I would have been billed in the US. I think it was about 100 euros and involved hours of tests for pneumonia/allergy/unknown respiratory issue.