MiDNI at Check-In: Accepting Spain's Digital ID Is Mandatory

A guest reaches your front desk, pats their pockets and pulls out a phone: they left the plastic DNI at home because they no longer need it. If reception answers by asking for the physical card, the conversation goes sideways, and the guest is the one in the right.

The change came with Royal Decree 255/2025. Its article 13.4 leaves no room for doubt about who the digital version of the DNI binds:

“Use of the Documento Nacional de Identidad in its digital version shall have the same legal effect for identification purposes. It shall allow identity to be established before the authorities, their agents and public officials, as well as in dealings with public administrations and with the private sector.”

Dealings with the private sector include your front desk. The third transitional provision of the same decree gave public and private entities twelve months to adopt the measures needed for that digital version to work properly². The decree entered into force on 2 April 2025, the day it was published in Spain’s official gazette, so the window closed on 2 April 2026.

What does not change is the communication to the Ministry. SES.HOSPEDAJES receives the same fields as before, and the responsibility for their accuracy is still yours.

What MiDNI is, the digital version of the DNI

MiDNI is the official app from Spain’s Interior Ministry and National Police that puts the Spanish national ID (DNI) on a phone. It is not a photo of the card and not a scan: it is the digital version of the document itself, fully valid for identification within Spain.

The holder activates it once with their physical DNI and its support number. From then on, when they need to identify themselves, the app generates a temporary QR code that stays active for only a few seconds. After that it expires and a new one has to be generated. That expiry is deliberate: it stops a screenshot from circulating as if it were a live document.

When you scan that QR, from another phone with MiDNI or from the official verifier at www.midni.gob.es³, you are not reading data stored on the guest’s phone. The app queries the unit that manages the DNI in real time and returns the information, which appears on screen for a moment and is not stored on the verifier’s device.

For anyone handling guest data that has one practical consequence: the flow is built so you never accumulate a static image of anyone’s card.

Where the DNI support number is printed

The support number is on the front of the card, the side with the photo, in the block of data on the right. The label next to it changes with the document version⁴:

• NUM SOPORTE on the DNI 4.0, the European format issued since 2021.
• NUM SOPORT on the DNI 3.0.
• IDESP on the electronic DNIs issued between 2006 and 2015.

The back carries the address, the place of birth and the machine-readable zone. Anyone hunting for the support number on the reverse will not find it on its own: it only appears inside that zone, embedded in a string of characters.

What the verifier sees: DNI age, DNI simple, DNI complete

MiDNI doesn’t always show the same thing. The guest picks the level before generating the QR, and that level decides whether you can fill in the report or have to ask again.

For a check-in you need the DNI complete level. If a guest shows you the age mode, ask them to switch, the same way you would ask someone to turn a passport to the data page.

Which documents you must accept as guest ID

Spain’s Interior Ministry closes the list in one line in its guest-lodging FAQ:

“The DNI for Spanish citizens (mandatory for people over 14), an Identity Document for EU citizens and a PASSPORT for foreign nationals.”

MiDNI doesn’t add a fourth category to that list: it is the DNI from the first line, presented on a different medium. So there is no basis for treating it as a second-class document, or for asking for the plastic as well just to be safe.

Day to day, accepting it breaks down into three concrete things.

• The front desk. Whoever handles in-person check-in must know what MiDNI is and how guests present it, the same way they recognise a passport. Recognising the QR isn’t optional.
• The data stays the same. RD 933/2021 requires the same fields as always, whether the data comes from a physical DNI, a passport or MiDNI.
• The report doesn’t change. SES.HOSPEDAJES receives exactly the same guest report. What changes is how identity is verified, not what is communicated to the Ministry.

Accepting the digital DNI does not shift the report’s liability

Data arriving verified by the police does not turn you into an intermediary without obligations. RD 933/2021 puts the accuracy of the report on the establishment, and settles in passing whether identity has to be established with a card:

“The partes and hojas shall be provided by the lodging or vehicle rental establishment, which shall be responsible for the accuracy of the data recorded in them, so that it matches the documents or systems establishing the identity of the persons concerned, which shall be exhibited or provided by the users of these services.”

Documents or systems: the 2021 decree already contemplated identity being established by a route other than the card. And “exhibited or provided by the users” is the guest’s side of the bargain: showing the QR is their part of it.

The fields you have to match are listed in Annex I of the decree, and they include two different numbers from the same document⁷:

• First name, first surname and second surname.
• Sex, nationality and date of birth.
• Identity document number.
• Support number of the document.
• Document type (DNI, passport, TIE).

The support number appears there as a field of its own, separate from the document number. That is the detail that makes MiDNI’s age mode useless for a check-in.

When nobody scans the QR: MiDNI and remote check-in

The MiDNI QR is built for an encounter. It lives a few seconds and needs somebody with a camera on the other side, so in an apartment with a key box, or on a two-in-the-morning arrival, there is nobody to show it to. MiDNI is not a remote check-in mechanism: it does not travel through your form and it does not land in your inbox.

That does not leave the guest report stranded, because remote verification does not run through the document. The AEPD, Spain’s data protection agency, accepts three mechanisms for authenticating what the traveller declares when nobody is in front of you⁸:

• a digital certificate belonging to the traveller;
• a check against the payment method details, which have to match what was declared;
• a security code sent to the guest’s phone or email.

Those are the same three routes for any guest, whether the DNI is on their phone or the plastic is in their wallet: what you verify remotely is the declared data, not the card.

There is also a fact in RD 255/2025 itself worth keeping to hand when someone tells you they only have the DNI on their phone. The digital version “shall be generated provided the holder has a valid physical document”¹. Anyone with MiDNI active has, by definition, a valid plastic DNI: they are never a guest without a physical document, and that card is where the support number they activated the app with came from.

For the manager, the rule is short:

• If you meet the guest, the QR works and saves time: ask for the DNI complete level and check it in seconds.
• If you don’t meet them, the QR never comes into play. You verify by certificate, by payment method or by code, and the document stays wherever it is.

The full framework, with what each mechanism requires, is in what RD 933/2021 allows without physical presence.

MiDNI cuts transcription errors in the guest report

There is a side effect that works in your favour. A whole class of SES.HOSPEDAJES rejections is born from data copied by hand off a document: a transposed digit in the support number, a date in the wrong format, a compound surname cut short.

When the data arrives digitally verified, it arrives as it is, not as it was typed. That removes the transcription class of rejections, which is not the only one: a report also bounces on a field copied correctly but left incomplete, or on an error in the portal itself. If your reports fail often, the error-code guide explains where each rejection comes from.

The MiDNI QR, mind you, doesn’t fill in your report: it is an identity check, not an integration with your check-in system. The real gain shows up when the guest’s data travels in digital form from the start, without passing through a keyboard at reception.

How to prepare your check-in for MiDNI in three steps

1. Train whoever receives guests. Everyone on the team should know MiDNI is valid identification, how guests present it, and that they must ask for the complete level.
2. Review your data flow. If you copy data by hand at the desk, the transcription error is still there: MiDNI doesn’t fix it.
3. Move check-in forward. With digital check-in before arrival, guests provide and sign their data before arriving, and reception is reduced to handing over keys.

FAQ

Can I demand the physical DNI if the guest brings MiDNI? No, you cannot demand the physical DNI when the guest brings MiDNI. RD 255/2025 gives the digital version the same legal effect as the physical document for identification, and says so expressly for dealings with the private sector, accommodations included. On top of that, the twelve-month window the decree gave entities to adapt closed on 2 April 2026, so there is nothing left to invoke.

Does MiDNI change the data the guest report requires? No, MiDNI does not change the data the guest report requires: the Annex I fields of RD 933/2021 are the same. What changes is how identity is verified at the desk, not what is reported to SES.HOSPEDAJES.

Can I keep a screenshot of the guest’s DNI from MiDNI? Keeping a screenshot of the guest’s DNI from MiDNI serves no purpose. The QR expires in seconds and the data isn’t stored on the verifier’s device: a screenshot is useless as live proof. What you do need to do is enter the fields RD 933/2021 requires into the report, just as with any other document.

Does MiDNI work for a check-in with nobody at the door? MiDNI does not work for a check-in with nobody at the door: its QR code lasts a few seconds and needs somebody with a camera to scan it, so with a key box there is nobody to show it to. Remote verification runs another way, the one the AEPD accepts: the traveller’s digital certificate, a check against the payment method details, or a security code sent to their phone or email. The report you send to SES.HOSPEDAJES is the same either way.

Do foreign guests use MiDNI? No, foreign guests do not use MiDNI: it is the digital version of the Spanish DNI. They keep identifying themselves with their passport or national ID card, as before.

What if the guest hasn’t activated MiDNI? If the guest hasn’t activated MiDNI, nothing happens: the physical DNI is still just as valid. MiDNI is one more option for the guest, not an obligation on them. The obligation is yours: to accept it when they present it.

What about minors travelling in the group? For minors travelling in the group, MiDNI doesn’t change the report rules: RD 933/2021 still requires registering them and, depending on age, capturing the responsible adult’s details. If the minor has a DNI, they can show it through MiDNI like any other guest; if not, they identify themselves as before. There is detail in how to register minors in the guest report.

Do I need a special reader for the QR? No, you don’t need a special reader for the QR: it is verified from another phone running the MiDNI app or from the official verifier on its website. No extra hardware is needed at reception beyond a device with a camera and a connection, because the check runs in real time.

With digital check-in, MiDNI means nothing to rebuild

If your check-in is digital, MiDNI arrives with your homework done: guests enter their data before arriving, the system validates it against the RD 933/2021 rules, and the report goes out on its own. That is how RegistroViajero works.

The document at the desk, plastic or on a phone, becomes what it always should have been: a seconds-long check.