Being allowed to stay is not the same as being sorted

Yes, as a Dutch citizen you may live in Spain without a visa.

• The first three months you can do so without any condition.
• After that a compulsory registration applies.
• If you don't work in Spain, you have to prove sufficient means and health insurance for that registration.

You get on the plane, you arrive, and nobody asks anything. That feels like simplicity, and it's the reason this process is systematically underestimated.

What may you do in the first three months?

As a citizen of the European Union you may stay in another member state for up to three months with a valid passport or identity card, without registering and without conditions. That's free movement, and it applies unconditionally. If you stay longer, something changes. And it's not a formality.

What applies after three months?

The Spanish Real Decreto 240/2007 obliges you to register in person in the Registro Central de Extranjeros, the central register of foreigners, within three months of entry. You do that at the immigration office or the police of your province. Conditions hang on that registration, and which apply to you depends on where your income comes from.

If you work in Spain, employed or self-employed, you're done. You fall under Spanish social security and with that both your income and your health cover are settled.

If you don't work in Spain, for instance because you work remotely for a Dutch employer, live off capital or are retired, you have to prove two things:

• Sufficient means for yourself and everyone coming with you, so that you don't need to rely on Spanish social assistance. There's no fixed amount: the assessment is individual, and under the Real Decreto the bar may never be higher than the Spanish social assistance level or the minimum pension.
• Health insurance that provides cover in Spain during your stay equivalent to that of the national health system. Pensioners meet that with the certificate that the country paying their pension bears the healthcare. For the Dutch that's the S1 form through the CAK.

You do that homework before departure. A Dutch health insurance stops as soon as you deregister from the municipality, and a bank statement isn't a bank certificate.

What	Term or amount
Stay without registration or conditions	up to 3 months
Registration in the Registro Central de Extranjeros, in person	within 3 months of entry
Fee for the registration certificate	€ 12 per person
Threshold for "sufficient means"	no fixed amount; at most the social assistance level or the minimum pension
Certificate of permanent residence	after 5 years of continuous legal residence, on request

Here lies the difference that defines the whole corridor. In a visa process you have to prove you may come. Here you may come, and have to prove you can stay. That's the same burden of proof, only at a different moment, and nobody reminds you of it.

What goes wrong if you leave it?

No letter comes and nobody is at the door. What happens is subtler: you get stuck in places where you don't expect it.

• The bank wants your registration certificate for an ordinary account instead of an account for non-residents
• The Spanish tax authority needs your NIE and your registration as soon as you become liable to tax here
• The traffic authority asks for it when you want to convert your driving licence or put a car in your name
• Your children's school allocates by address, and that address comes from your municipal registration

Each of those things can wait. But they all wait at the same time.