Spain rewards patience and punishes assumptions, and most of the trouble people run into comes down to a handful of predictable missteps.
The first is underestimating how slow and fragmented Spanish administration can be. Rules that apply in Madrid are not always applied the same way in a small town in Galicia or Andalucía, and offices often run on their own logic regardless of what a government website says. As EU citizens we do not need a visa to live here, but we still need to register as residents, get a NIE for anything involving taxes or property, and sign the padrón at the local town hall. None of this is difficult in principle, but all of it takes longer than expected, and showing up without the right photocopies means starting the queue again another day.
Taxes catch out a lot of Europeans who assume that because they are used to reasonably simple systems back home, Spain will be similar. Stay more than 183 days in a calendar year and you are generally considered a tax resident, which means declaring worldwide income here, not just what you earn locally. This is one area where a good local gestor or accountant earns their fee many times over, and where guessing based on how things worked in your home country tends to end badly.
Opening a Spanish bank account early is not optional in practice. Utilities, phone contracts, and even some healthcare paperwork assume you have a local IBAN, and trying to run daily life through a foreign account gets old fast.
Language is the mistake most often underestimated. In the bigger coastal cities and tourist areas you can get by in English for a while, but away from those pockets, and certainly in rural areas, that comfort disappears quickly. Town hall staff, doctors, and neighbours will mostly speak Spanish or the local regional language, and a bit of effort here changes how you are treated, not just how well you communicate.
Healthcare is more straightforward for us as Europeans than it is for people arriving from outside the EU, since an EHIC or S1 form covers a good deal in the early stages depending on your situation. But it is not automatic forever, and once you are working and paying into Spanish social security, or registered as a resident long term, the details of what is covered and how change. It is worth understanding this before you need it, not after.
None of these mistakes are dramatic on their own. What they have in common is that they all come from applying assumptions from home to a system that runs differently, and that gap is usually where the frustration starts.
