A listing for a Spanish clinic crossed my desk not long ago. It did something most ads never do: it described the licence by unit code. The code it gave was the catalogue's residual one — the "other units" drawer — while the services it described belong to a unit the catalogue defines by name.
In Spain's official catalogue of health-care units, aesthetic medicine has its own code — U.48. The residual category is U.900: «otras unidades asistenciales», the drawer for units that fit none of the defined ones. An ad that describes aesthetic-medicine services while giving a residual code is not wrong by that fact alone — but it has raised a question.
That difference is not an accusation, and it may have an entirely ordinary explanation. But it is a question a buyer can test against a public register before a single euro moves — and for a clinic, the licence is not paperwork on the side. It may be central to what the buyer thinks is being bought.
Health centres in Spain are authorised unit by unit
The framework is Real Decreto 1277/2003. Its annexes classify and define every type of health centre and every unidad asistencial — the named units of care a centre is authorised to offer. The authorisation is not one rubber stamp for "a clinic":
«La autorización de funcionamiento será concedida para cada establecimiento y para cada centro sanitario, así como para cada uno de los servicios que constituyen su oferta asistencial, debiendo ser renovada, en su caso, con la periodicidad que determine cada comunidad autónoma.»
— Art. 3.2, Real Decreto 1277/2003, consolidated text · BOE, retrieved 12 Jul 2026. Unofficial translation: the operating authorisation is granted for each establishment and for each health centre, as well as for each of the services making up its care offer, and must be renewed, where applicable, at intervals set by each autonomous community.
So the working question about any clinic for sale is not "does it have a licence?" but "which units is this centre authorised for, in whose name, and since when?"
U.48, U.47 and U.900 — three codes the catalogue defines very differently
Annex II of the same decree defines the units. Here are the three that matter for an aesthetic clinic, in the catalogue's own words:
«U.48 Medicina estética: unidad asistencial en la que un médico es responsable de realizar tratamientos no quirúrgicos, con finalidad de mejora estética corporal o facial.»
«U.47 Cirugía estética: unidad asistencial en la que un médico con la especialidad en Cirugía plástica, estética y reparadora u otra especialidad quirúrgica o médico-quirúrgica […] es responsable de realizar tratamientos quirúrgicos, con finalidad de mejora estética corporal, facial o capilar.»
«U.900 Otras unidades asistenciales: unidades bajo la responsabilidad de profesionales con titulación oficial o habilitación profesional que […] llevan a cabo actividades sanitarias que no se ajustan a las características de ninguna de las unidades anteriormente definidas, por su naturaleza innovadora, por estar en fase de evaluación clínica, o por afectar a profesiones cuyo carácter polivalente permite desarrollar, con una formación adecuada, actividades sanitarias vinculadas con el bienestar y salud de las personas […]»
— Annex II, Real Decreto 1277/2003, consolidated text · BOE, retrieved 12 Jul 2026. Unofficial translation: U.48, aesthetic medicine — a unit in which a doctor is responsible for non-surgical treatments for bodily or facial aesthetic improvement. U.47, aesthetic surgery — a unit in which a doctor with the relevant surgical specialty is responsible for surgical treatments. U.900, other care units — units, under professionals with official qualifications or professional accreditation, carrying out health activities that do not fit any of the defined units: innovative in nature, in a clinical-evaluation phase, or belonging to versatile professions working on wellbeing and health within centres classed as sanitary.
Three observations follow, and each can be framed first as a buyer's screening question:
First: "aesthetic medicine" as a defined unit is U.48, and the definition puts a doctor in charge of non-surgical treatments. Second: where an advertised service is surgical, U.47 is the catalogue code to ask about, with its own specialty requirements — a different unit from U.48. Third: U.900 is, by definition, the unit for activities that do not fit the defined categories. A centre authorised under U.900 may be operating perfectly lawfully — the definition exists precisely because lawful activities can fall outside the named units — but "U.900" and "a licensed aesthetic-medicine unit" are not the same claim.
The public register is the starting point
You do not have to take the ad's word, or the seller's. The decree created a national register of authorised centres, and made its character explicit:
«El Registro general de centros, servicios y establecimientos sanitarios tendrá carácter público e informativo.»
— Art. 5.4, Real Decreto 1277/2003, consolidated text · BOE, retrieved 12 Jul 2026. Unofficial translation: the general register of health centres, services and establishments shall be public and informative in character.
The register runs online as REGCESS, and its search form is a useful first screen: you can search by autonomous community, town, street, centre type, centre name — and by the unit of care offered, U.48 and U.900 included. The autonomous communities keep their own registers too, feeding the national one, each with its own registration numbering; ask for the relevant regional number. Your step: before relying on the licence in any price discussion, find the centre in the register and read its entry — the authorised units, the dates, and the holder. If the entry and the ad tell different stories, that is your first written question to the seller — a question, not a conclusion.
There is also a rule about advertising itself. Art. 6.2 of the decree restricts health-suggestive publicity to authorised centres, limits it to the services and activities actually authorised, and requires it to carry the registration number granted by the regional health authority, or the number of a specific health-advertising authorisation. A third-party portal listing is not necessarily the centre's own regulated publicity — but if the material you are relying on shows no checkable registration number anywhere, ask the seller to provide it.
The authorisation names a holder — and holders change by authorisation, not by handshake
For a buyer, the sharpest edge is this line of art. 3.2:
«La autorización sanitaria de modificación es la que solicitarán los centros, servicios y establecimientos sanitarios que realicen cambios en su estructura, en su titularidad o en su oferta asistencial.»
— Art. 3.2, Real Decreto 1277/2003, consolidated text · BOE, retrieved 12 Jul 2026. Unofficial translation: the modification authorisation is the one that health centres, services and establishments must request when they make changes in their structure, in their ownership/holder, or in their care offer.
Read it against the phrase every clinic listing loves — "licences already in place". The authorisation sits with a named holder. If your deal transfers the business to you or to your company, the holder changes — and art. 3.2 treats changes in the holder as a modification-authorisation issue, handled under the procedure of the region. How long that takes, what it requires, and what may lawfully operate in the meantime are questions for a Spanish health-regulatory lawyer before completion — not discoveries for the week after. And if the deal is structured as a purchase of the company's shares so that the holder never changes, remember what that structure means: the company arrives with its entire history, which is a different diligence exercise, not a smaller one.
The patient base is not an ordinary asset
A café's goodwill is its regulars. A clinic's "client book" is something else in law — patient records are health data:
"Processing of personal data revealing racial or ethnic origin, political opinions, religious or philosophical beliefs, or trade union membership, and the processing of genetic data, biometric data for the purpose of uniquely identifying a natural person, data concerning health or data concerning a natural person's sex life or sexual orientation shall be prohibited."
— Art. 9(1), Regulation (EU) 2016/679 (GDPR) · EUR-Lex, retrieved 12 Jul 2026. Art. 9(2) then lists the exceptions under which such data may lawfully be processed.
The prohibition is the rule; an art. 9(2) route is needed for such data to be processed at all — and that route does not stand alone: the controller still needs a lawful basis under art. 6 and has the rest of the data-protection duties besides. Which route, if any, carries a patient database from one operator to another, on what conditions and with what obligations attached, is a legal question that depends on how the deal is built. What this means for a buyer is simple to state: if a meaningful part of the asking price is "the patient base", the lawful route by which that base can reach you should be established before the price is agreed, not after. A patient list handed over informally may create data-protection exposure rather than transferable value.
Read the mismatch as a question, not a finding
A code in an ad is a claim by whoever wrote the ad — it can be a typo, a shorthand, an old code, or exactly what the register says. U.900 authorisations exist because the catalogue itself provides for activities that fit no named unit. Nothing in this note says, or should be read as saying, that any particular clinic is unlicensed or mis-licensed. The point is narrower and more useful: the register is public, the ad is checkable, and a discrepancy between "the licence the ad describes" and "the authorisation the register lists" is something you can often identify for free, from your desk, before any deposit — and then put to the seller and, where needed, to the regional health authority.
Clinics are also exactly the kind of business where a desk screen has hard limits. Health-care regulation is regional, inspection-driven and specialised; whether a given service may be provided under a given unit, and what a change of holder requires in a given community, is work for a lawyer who practises in that field. That carve-out is not small print — it is part of the answer.
What to establish before you make an offer on a clinic
The authorisation record itself. Ask for the centre's registration number and its current authorisation, and read the register entry next to it: the named holder, the authorised units, the dates. The ad's description of the services should map onto units the centre actually holds.
Who the holder is — and what your deal does to that. If the holder is the seller's company and you are buying assets, the change of holder is a regulatory step with its own timeline, not a line in the contract. Ask, in writing, how the seller proposes the authorisation reaches you, and have a Spanish health-regulatory lawyer test the answer.
The units behind each advertised service. Where the marketing lists treatments — injectables, laser, surgery, whatever it may be — ask which authorised unit each is provided under, and who is the responsible professional named for it.
The lawful route for the patient records. Before "the patient base" is priced, ask how it would lawfully transfer, who has advised on that, and what patients have been or would be told. If the answer is a shrug, the asset may not be transferable in the form the price assumes.
Whether the licence in the ad matches the authorisation in the register is a desk question — and I check it against the named public registers before you commit. I map what the public record shows about the specific business, what it cannot show, and exactly what to demand from the seller first.
Check my deal →Basis: the consolidated text of Real Decreto 1277/2003, de 10 de octubre (last consolidation update 26 March 2026), retrieved from the Boletín Oficial del Estado on 12 July 2026 and quoted verbatim above; the public REGCESS register search of the Ministry of Health, accessed the same day; and art. 9 of Regulation (EU) 2016/679, retrieved from EUR-Lex the same day. The BOE consolidated text also carries a historical nullity note concerning the 2006 wording of the U.900 reference (annulled by an Audiencia Nacional judgment of 26 September 2007); that note does not change the current consolidated definition quoted here. The listing mentioned at the top is a real advertisement read in full; it is deliberately not identified, its details are blurred, and nothing here states or implies any finding about it or about any person or business — a mismatch between an ad and a register entry is a question to ask, and only the register and the regional health authority can answer it. General information about how the rules work, not legal advice: health-care licensing is regional and specialised, and what any authorisation covers, or requires on a change of holder, is for a Spanish health-regulatory lawyer to confirm on the facts of a specific deal. Not a statement about any current listing.