How to set up electronic invoicing in your company: a step-by-step guide

If you manage a company's finances, you know that implementing electronic invoicing is a legal obligation. With the Crea y Crece Law and the Verifactu regulation, B2B electronic invoicing will gradually become mandatory starting in 2026. In this guide, you will see, step by step, how to implement electronic invoicing, how long it takes, and what role the digital certificate , and what the best solutions are. 

Why do you need to implement electronic invoicing now?

Before getting into how to set up electronic invoicing, we need to frame the "why":

• The Create and Grow Act (18/2022) requires B2B transactions to be carried out using electronic invoicing, with shorter deadlines for large companies. 
• The Royal Decree 1007/2023 regulates the requirements for invoicing systems (Verifactu) and establishes that, from 2025–2026, only software approved by the AEAT (Spanish Tax Agency) may be used.
• The electronic invoice must meet certain formal requirements (Facturae format or other structured XML formats, signature, QR code, mandatory fields, etc.).

For a large company, this means:

• Integrate the issuance and receipt of e-invoices with the ERP.
• Connect with external platforms (FACe, TicketBAI, Peppol, private networks, customer portals, etc.).
• Ensuring the traceability and preservation of invoices for years.
• Standardize billing software .

In other words, in addition to downloading a program, we are dealing with a project that requires processes, technology, and governance.

How to implement electronic invoicing in a large company? Project phases

Below is a complete step-by-step guide for installing electronic invoicing (both for issuing and receiving). 

1. Functional and technological diagnosis

1. Maps systems: ERPs (SAP, Oracle, Navision/Dynamics, Sage, in-house, etc.) and satellite tools (CRM, purchasing tools, supplier portals, etc.).
2. Map billing flows. Invoices with and without orders, national and international B2B, B2G (public administrations), companies, cost centers, countries, and currencies.
3. Review legal requirements by country.

This will give you a matrix of requirements that will help you choose a supplier.

2. Solution design and architecture

• Decide between multi-client SaaS model (easyap, B2Brouter, or Edicom, etc.) integrated with your ERP or a customin-house development (not recommended due to cost and maintenance).
• Define input and output formats (Facturae, UBL, EDI, custom XML, PDF, etc.) 
• Define the connection strategy with FACe, TicketBAI, and SII, Peppol and customer and supplier portals.
• Decide on the cost model: fixed license + maintenance or pay-per-use with no initial investment, as with easyap (variable cost per invoice processed). 

In large companies, this phase lasts between 2 and 4 weeks, if the scope is multi-country.

3. Selection of electronic invoice provider

Third, compare options. This simplified table will help you: 

Supplier	Ideal for…	Strengths	Limitations
easyap	Medium and large companies, multinationals, and organizations with multiple ERPs.	Advanced integration with ERPs, pay-per-use with no initial investment, rapid implementation, scalability, and specialized support.	It requires a solid initial definition of processes in highly complex structures.
Holded	SMEs seeking rapid implementation.	Intuitive interface, low learning curve, and immediate start-up.	It is not designed for multinationals or complex integrations.
Declaring	Self-employed workers and micro-enterprises.	Easy to use, tax-focused, and low cost.	Not well suited for corporate or multi-ERP environments.
B2Brouter	Companies and freelancers who need to send and receive B2G electronic invoices, or large customers without extensive customization.	Simple plans, good compatibility with Facturae and FACe, and standard connections.	Limited customization for companies with complex processes.
Edicom	Large companies with international operations.	Well-established and robust global platform for multi-country tax compliance.	Longer projects and greater initial investment.

4. Installing the digital certificate for electronic invoicing

On the other hand, the installation of the digital certificate is essential, as it guarantees the authenticity and integrity of the e-invoice. To do this: 

1. Request the certificate from a qualified entity (FNMT, Camerfirma, ACCV, etc.). 
2. Verify your identity in person (registration office) or online. 
3. Download the certificate in your browser or in a secure storage location.
4. Install it on your billing systems. There are solutions where you upload the file and the system signs for you. In others, such as easyap, you can sign with the issuer's certificate or delegate the signature to the portal's own certificate, which is very convenient.
5. Signature testing and validation. Send test invoices to FACe or to your customers' approval environments.

5. Integration with ERP and workflows

This is where the implementation of electronic invoicing affects day-to-day processes:

• Define which events trigger the generation of electronic invoices (e.g., posting invoices in SAP).
• Establishes the interfaces for exporting invoice data from the ERP to the supplier (XML/CSV/Excel files, web services, specific connectors, etc.) and statuses (accepted, rejected, paid, etc.).
• Configure business rules (by country, customer type, delivery channel, etc.) and internal approval workflow (especially for invoice receipt).

With easyap, this process is simplified because easyei is designed as an intermediate layer between your ERP and the outside world. Invoices are generated in the ERP without changing the current process. They are then exported to the easyei portal, where:

1. They are converted into the appropriate format (Facturae, EDI, UBL, specific customer formats).
2. They are signed electronically.
3. They are sent via the agreed channel (FACe, Peppol, email, customer portal, etc.).

For invoice reception, easyap unifies channels (paper, email, e-invoice) in a single portal with an approval workflow and subsequent integration with the ERP.

6. Pilot, deployment, and training

To complete the installation of electronic invoicing: 

1. Make a short pilot with 1–2 companies and a small group of customers or suppliers. 
2. Make a progressive rollout to other companies and countries.
3. Finally, it offers highly specific training to finance and systems teams to ensure that the process is operational from day one.

How long does it take to set up electronic invoicing?

As for the time, there is no single answer, but to give you a reference:

• In simple projects (a company, a country, without complex integrations, etc.) with lightweight solutions, you can issue e-invoices in days or hours.
• In medium and large projects (multiple companies, ERP integration, connection to multiple portals, etc.):
  • Analysis + design phase: 3–6 weeks.
  • Technical integration and pilot: 4–8 weeks.
  • Full rollout: 3–6 months, depending on the number of countries and systems.

With easyap, there are two levers that shorten deadlines:

• It is a cloud-based SaaS platform, with no initial investment in infrastructure or heavy licenses.
• You can register on the issuance portal with a valid digital certificate in less than three minutes, which gives you the possibility to start testing quickly ("short-term implementation").

Checklist for CFOs: Are you ready to implement electronic invoicing?

To conclude, here is a list of tasks that you should review and carry out. It serves as an internal guide before choosing a provider:

• Do you know in which countries and for which companies you will need e-invoicing in the next 12–24 months?
• Are you familiar with the national and international legal requirements ?
• Do you know which systems you generate your invoices (ERPs, ordering tools, CRM, etc.)?
• Have you defined which internal teams will lead the project (finance, IT, tax, purchasing, etc.)?
• Do you have a plan for obtain and install digital certificates and test the electronic signature?
• Do you want a SaaS model with no initial investment or a more robust platform with a turnkey project?
• Have you calculated the expected ROI in terms of time savings, error reduction, and improved collections?
• Do you have a 3–6 month roadmap to move from pilot to full deployment?

In this context, easyap is a highly competitive alternative. We combine experience in multiple sectors and countries, a pay-per-use SaaS model, and quick installation based on your ERP and functional and technical support throughout the implementation process. If you would like to learn more about how to implement electronic invoicing in your company and reduce risks, contact us.