— Essay Nº3, on the mechanics of the obligation

On the mechanics of the obligation

A flowing account of the five operative stages — alta, capture, signature, transmission, retention — through which the host discharges the duty imposed by Real Decreto 933/2021.

The mechanics of compliance with the present regulation may be apprehended, with some loss of nuance but no real distortion, as a sequence of five operative stages: the alta, or enrolment, of the establishment on the relevant platform; the capture of guest data at the point of check–in; the obtaining of the traveller’s signature; the transmission of the data to the system within the prescribed window; and the retention of the documentary file for the period set by the regulation. Each of these stages carries its own procedural texture, and it is the cumulative observance of all five that the inspecting authority will examine.

The alta is the first and, in a sense, the most delicate of the five. Before a single traveller’s data may be communicated, the establishment must be registered as a prestador de servicios de hospedaje on the relevant platform — SES.Hospedajes for the fifteen autonomous communities that fall under the central regime, or the equivalent regional system in Catalonia and the Basque Country. Enrolment is effected through the Sede Electrónica del Ministerio del Interior, and it presupposes a means of strong electronic identification — either a digital certificate issued by the Fábrica Nacional de Moneda y Timbre, or activated Cl@ve credentials. The non–resident owner, in particular, will discover at this point that the regulation operates upstream of the digital infrastructure required to comply with it: without an active NIE and the personal presentation required to obtain either credential, the owner cannot, in person, enrol.¹ The standard remedy is the designation of an authorised representative — a property manager, a gestoría, or a specialised service — and the inscription of the corresponding mandate, prior to the first communication.

The capture of guest data, at the moment of check–in, is the operative heart of the regulation. The regulation prescribes a catalogue of some fifteen to twenty fields per traveller of fourteen years of age or older — full name, document type and number, date of birth, nationality, sex, address, telephone, the manner and identifier of the reservation, the means of payment, the dates of arrival and departure, and so forth. Particular attention is owed, in the case of the Spanish DNI, to the número de soporte: this is a six–character identifier printed on the rear of the card and on the chip, distinct from the número de DNI itself, and frequently confused with it by those new to the procedure. The corresponding datum for foreign passports is the document number; for the European identity card, the support number; for the Spanish residence card, the NIE support number.² The arrival timestamp must be recorded in the ISO 8601 format that the platform accepts, that is, in the form YYYY–MM–DD HH:MM:SS.³

The signature of the traveller is the third stage, and the one in which the regulation most clearly reveals the analogue origins it inherits. Each traveller aged fourteen or over must sign the parte; the signature may be wet, upon a paper retained by the host, or electronic, in one of two principal forms — a digital signature applied through a recognised provider, or, more commonly in practice, an OTP–confirmed pre–arrival check–in flow in which the traveller, having received a one–time password upon arrival or shortly before, validates by that means the data that the host has previously captured. The signed parte is conserved by the host as part of the three–year file; it is not transmitted to the platform. Only the data fields themselves are uploaded.⁴

The transmission of the data to the platform must be effected within twenty–four hours of the moment of check–in — a period that runs continuously and does not pause for weekends, holidays, or, in the strict letter, technical incidences (although, in the practice of the inspecting authority, well–documented platform outages have been admitted as exonerating). The technical channels available to the host are three: an interactive web form for low–volume operators, a structured XML upload for those who export from property–management systems, and a programmatic API for high–volume operators and platforms of intermediation. The digital platforms — Airbnb, Booking, Vrbo, Expedia — discharge their parallel obligation by way of the API, and their communications run upstream of the host’s.⁵ It bears emphasis that the platform’s communication of a booking does not discharge the host’s obligation to communicate the subsequent arrival: the two are distinct and additive.

The retention of the documentary file is the final stage, and the one that distinguishes the professional host from the merely occasional one. The professional host — that is, the host who exercises the activity in a habitual manner and is inscribed in the tourism registry of the relevant autonomous community — must conserve, for a period of three years from the close of each stay, the signed parte, the transmission acknowledgement issued by the platform, and any ancillary documentation that bears upon the communication. The format of conservation is not prescribed; both paper and electronic archives are admitted, provided that the documents are legible, complete, and retrievable upon inspection. The non–professional host is bound to communicate and to obtain signature but not to retain the file for the three–year period — though, in practice, the host who has the documents will rarely wish to discard them.⁶

Two further observations may be useful. The first is that the regulation operates per–stay, not per–property and not per–guest–in–the–aggregate: every distinct arrival generates its own twenty–four–hour clock, its own data set, its own signature, and its own transmission record. The second is that, at the volume threshold beyond which manual processing ceases to be sustainable — in the experience of the operators with whom this material has been discussed, that threshold lies near three to five concurrent properties, depending on average tenancy length — the integration of property–management software with the platform’s API becomes not an optimization but a structural necessity.

1. The strong–identification requirement for access to SES.Hospedajes is set out in the conditions of use of the Sede Electrónica del Ministerio del Interior; the admitted credentials are the digital certificate of the FNMT and activated Cl@ve credentials. Without one of the two, direct enrolment is not possible. ↩
2. The data–capture catalogue, and the requirement to record the número de soporte as distinct from the número de DNI, derive from the annexes of Real Decreto 933/2021 and from the operational guidance of the Ministerio del Interior. ↩
3. The platform accepts the arrival timestamp in ISO 8601 format (YYYY–MM–DD HH:MM:SS), in accordance with the technical specifications published by the Ministerio del Interior for the API and XML upload channels. ↩
4. The signature requirement, for travellers of fourteen years or older, is articulated in the body of the regulation. The signed parte is retained by the host as part of the three–year file and is not itself transmitted to the central system. ↩
5. The three channels of transmission — interactive web form, XML upload, and programmatic API — are documented in the technical specifications of SES.Hospedajes. The digital platforms of intermediation discharge their parallel obligation under article 4 of the regulation. ↩
6. The three–year retention obligation, binding upon professional hosts, is set out in the regulation. The non–professional host is not bound to retain, but the question of qualification as professional or non–professional is itself a matter for case–by–case analysis. ↩