Do I need to register friends & family who stay free of charge?

Yes. If you operate the property as tourist accommodation, everyone who sleeps there must be registered — friends and family included, whether or not they pay you a penny.

This catches people out because the definition of a lodging activity does mention money: article 2.1 describes it as providing space for the night a cambio de un precio, contraprestación o compensación. Read on its own, that looks like a per-guest payment test. It is not. It describes the activity you are carrying on, not each individual stay within it.

The rest of the decree makes that plain. Article 1 covers those who carry on lodging activities profesionalmente o no. Article 3 applies it sea cual fuere la modalidad, la personalidad del titular o el modelo de organización — whatever the arrangement, whoever the owner, however it is organised. And article 4.1 puts the duty on the holder of the activity to collect the details of las personas usuarias de las mismas — the people using it. There is no exemption there for a guest who did not pay. Article 2.1.b puts apartments, bungalows and similar tourist accommodation squarely inside the definition.

So the question is not "did this guest pay?" but "is this property being run as tourist accommodation?". If it is, your friends and family are users of that activity. The only way the obligation falls away is if you stop operating it commercially altogether — at which point there is no lodging activity to report on.

Every person staying is registered, including children of all ages. Guests aged 14 and over sign for themselves; for younger children, an accompanying adult provides their details. There is more in our guide to children, babies and teenagers.

Watch the deadlines, because there are two of them and not one. Article 6.3 requires the data within 24 hours of making the booking or contract — or of cancelling it — and again within 24 hours of the stay beginning. A free stay for family still has both. If a guest cannot provide their data, you remain responsible for collecting and submitting it; see when a guest cannot register their data.

For the wider picture, see which guests must be registered.