Interoperability in the e-invoicing ecosystem in Spain promoted by the ‘Crea y Crece’ Law

Last updated: 20 de April de 2026

If you thought replacing animal milk with plant-based drinks was a revolutionary change, get ready for what 2027 has in store for us thanks to the “Crea y Crece” Law (Create and Grow Law).

With the approval of Royal Decree 238/2026, the Government has triggered the final countdown for the mandatory implementation of electronic invoicing in B2B transactions. This measure is not a simple administrative requirement: it will be the cornerstone of a national strategy to eradicate commercial late payments and accelerate the digitalization of the business fabric.

This new regulation is set to break down technological barriers by imposing a model that ensures interoperability between private platforms, guaranteeing that data flows without friction.

But, technically speaking, what requirements lie behind this interoperability? How will platforms communicate in this new ecosystem?

Let’s find some answers.

Table of contents

The end of digital islands: The new B2B standard

Until now, invoice digitalization in the private sector has functioned as a collection of digital islands, as if those islands were in the wild west. Each company imposed its own rules: a specific format, a particular network, or even the obligation for suppliers to register in a proprietary portal just to get paid.

This is the ultimate nightmare for both developers—due to ad-hoc integrations, fragmented APIs, etc.—and for CFOs and administrative staff, facing information silos and manual processes.

With the entry into force of the “Crea y Crece” Law and its recent regulatory development through Royal Decree 238/2026, we can say there is a new sheriff in the national invoicing town. In other words: Spanish regulations are taking a giant leap forward by establishing a system where interoperability is not an option, but a legal obligation to ensure that any issued invoice reaches its destination, regardless of the platform used by each company.

The law seeks to transform commercial relationships by digitalizing accounts receivable and accounts payable on a massive scale.

However, as always, not all that glitters is gold. Or rather, it might be, but mining that gold takes work. Connecting with thousands of customers and suppliers using different ERP systems or exchange platforms is a considerable technical architecture challenge.

In this context, having a partner like B2Brouter—capable of eliminating the technical friction of the process and handling the translation of your data into the language your client (or the Tax Agency itself) needs—will save you major headaches.

“But Capde, I think I can handle it, I just need you to tell me what it consists of.”

Message received!

The rules of the game: Articles 8 and 9 of the Decree

For electronic invoicing to be truly universal, Royal Decree 238/2026 establishes that the system cannot be a closed network. The regulation imposes strict interconnection obligations to ensure that information flows without artificial barriers.

The obligation to interconnect (Art. 8)

The law is clear: private platform operators are obliged to interconnect with any other platform in the system when a client requests it. This means that if your company uses one platform and your supplier uses another, both platforms must “build a bridge” so that the invoice reaches its destination.

And no cheating! The law explicitly prohibits one platform from charging another for these connections, preventing an increase in operating costs simply for having a wide and diverse supplier base. Furthermore, this connection must cover, at a minimum, the exchange of invoices and their mandatory statuses (acceptance or rejection, and payment).

Procedure and deadlines (Art. 9)

To prevent platforms from delaying these connections, the regulation sets a maximum period of one month for the interconnection to be operational from the time it is requested. During that month, if the connection is not yet direct, the platform must use the public electronic invoicing solution as a transitional route to deposit the invoices.

We won’t go into the pros and cons of this public solution now, but it is worth noting that its use would imply manual tasks that contradict the digital agility promoted by the law.

Interoperability will be mandatory. Implementing it doesn’t have to be complex.

With the right partner, you can comply with the regulation without turning it into a never-ending internal project.

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The Tower of Babel of formats

One of the greatest technical challenges of the “Crea y Crece” Law is that it does not impose a single file format; instead, it recognizes the reality of different sectors that already use consolidated standards. This forces companies to have a very high semantic and technical adaptation capacity.

The electronic invoice must be a structured computer message that conforms to the EN16931 semantic data model. The valid syntaxes are:

UBL (Universal Business Language): The most widespread international standard and the reference syntax for the AEAT public solution.
CII (Cross Industry Invoice): XML format created by the United Nations CEFACT.
EDIFACT: Very common in sectors such as retail or automotive due to its historical penetration.
Facturae: The current standard for invoicing Public Administrations in Spain.

What does this mean for the development department of any invoicing software? It means that to claim full compliance with the regulations, they will have to program and maintain data mappings for four different formats—a task that consumes critical resources.

Security and protocols: AS4, signatures, and “Non-Repudiation”

In a system where paper invoices disappear, security is not just a matter of privacy, but of legal integrity. Royal Decree 238/2026 raises the technical requirements to ensure that no one can alter an invoice once it has been issued.

This implies that the law requires private platforms to use secure protocols for data transmission. Although many companies are used to traditional REST APIs, the regulation focuses on AS4 (Applicability Statement 4).

What is AS4 and why does it matter?

It is a messaging standard based on web services (ebMS 3.0) that offers advanced security, acknowledgment of receipt, and, above all, non-repudiation. This is important because, unlike a simple file transfer, AS4 guarantees that both the sender and the receiver have irrefutable technical proof that the message was delivered and received correctly. The Fort Knox of data.

Advanced electronic signature (Art. 7.3)

All electronic invoices issued through private platforms must be signed with an advanced electronic signature or an advanced electronic seal. This guarantees the authenticity of the origin and the integrity of the content, ensuring the document has not been modified since its signing.

B2Brouter: Your trusted technological partner

We won’t lie; the transition to mandatory electronic invoicing can be difficult—especially for those trying to walk that path alone. In a context of strict technical requirements and status communication deadlines of barely 4 calendar days, having the right technological partner transforms this obligation into an immediate operational advantage.

This is where B2Brouter comes into play:

Guaranteed and Free Interconnection: In compliance with the new model, B2Brouter eliminates technological “silos,” allowing you to connect with any client or supplier regardless of the platform they use.
Technical and Legal Rigor: Our platform already supports the required structured formats (Facturae, EDIFACT, UBL, and CII) and guarantees the integrity of your documents through advanced electronic signatures.
Real-Time Status Management: We automate the communication of acceptance, rejection, and effective payment of your invoices, ensuring you always meet the reporting deadlines for the AEAT public solution.
Scalability and Security: With high-level security certifications (ISO 27001), we offer a robust infrastructure that protects your data and ensures business continuity.

The deadlines are already set: July 2027 for large companies and July 2028 for the rest of the business fabric. Don’t wait for the regulations to become an emergency; get ahead with B2Brouter and turn digitalization into the efficiency engine your company needs to grow without limits.

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