Which guests must be registered

Everyone who sleeps there

There is no "lead guest only" rule and no age below which a person stops counting. If someone sleeps in the property, their details form part of what you send.

The age rule is about signing, not about children

This is the most misreported detail on the whole subject.

Fourteen is the age at which someone signs their own form. It is not an age below which you stop collecting details.

The next article removes any doubt. The record must include the details of under-fourteens too.

So a family of four with two small children means four people reported, and two signatures.

The under-18 box almost everyone misses

There is a required field for the relationship between the guests — whether they are a family, a couple, friends and so on. You only have to fill it in when someone in the party is a minor.

Here is the catch. "Minor" here means under 18, not under 14.

So a booking with a sixteen-year-old needs that box filled in, even though the sixteen-year-old signs for themselves. Leaving it blank is one of the most common reasons a report gets rejected.

Friends and family, and stays where nobody pays

This comes up constantly, and the honest answer is more interesting than the confident answers you will find elsewhere.

The rules do not apply to "holiday rentals" as such. They apply to providing accommodation, and the law defines that by what is given in return.

So the test is whether something changes hands. Not whether you happen to be there. Three things follow from that, and they are not what most people expect.

"Free" is a narrower idea than it sounds

Payment or compensation means more than money. If they cover the cleaning, pay the electricity bill, or let you use their place in return, something has changed hands.

A stay only sits outside these rules if genuinely nothing comes back to you.

Tourist properties are swept in anyway

The same article goes on to say that certain things are included "in any event" — and among them are apartments and similar properties of a tourist nature.

There is a real argument, then, that a property being run as a holiday let is covered whatever a particular guest paid. As far as we can establish this has never been settled by a court. It is a genuine gap in the wording rather than a question with a hidden answer.

"Were you there?" is a rule of thumb, not the rule

Long stays — and a point that catches people out

How long someone can stay before your let stops counting as a "tourist" let is decided by your tourist licence and your regional government — never by SES.Hospedajes. The two get talked about as if they were one thing. They are not.

The limits vary enormously between regions, and there is no national day count at all — nothing in the Ley de Arrendamientos Urbanos sets one. Catalonia works to 31 days. Andalucía uses two months. The Canary Islands use no day count, applying a frequency test instead. The Valencian rules are among the tightest.

That matters mainly because of one very widely repeated error: the "31 days" figure you will see quoted as though it were Spanish law is only the Catalan rule. If your property is not in Catalonia, it does not apply to you.

We have researched these thresholds region by region but have not yet published the underlying decree references, so treat the figures above as orientation rather than as something to rely on for a specific let. Your regional tourism authority is the authority on your own property. A page setting out each region properly is on the list.

Now the part that surprises people.