Mandatory e-invoicing: which businesses must file a declaration by October 12

Under the current regulatory framework, the declaration does not apply to all businesses. From October 1, it will be required exclusively from businesses with gross revenues of up to €1 million, based on the 2023 tax year, that choose to make use of the adjustment period through the end of 2026 and continue, in parallel, to issue invoices using the existing methods.

Which Businesses Must File the Declaration

The AADE clarifies that, as of October 1, 2026, the “Declaration of Commencement of Electronic Issuance of Documents” must be submitted by businesses that meet both of the following conditions.

First, their gross revenues for the 2023 tax year must not exceed €1 million.

Second, they must opt for the gradual compliance period, which runs from October 1 through December 31, 2026. During this period, businesses may continue to issue invoices using the existing methods alongside electronic invoicing.

The declaration may be submitted until October 12, 2026.

Who Does Not Need to File

By contrast, businesses that, from October 1, 2026, issue all their invoices exclusively through the timologio or myDATAapp applications are not required to submit the declaration.

In other words, the declaration is linked to the decision to make use of the transitional period, rather than to electronic invoicing itself.

If a business has already switched exclusively to electronic invoicing through these applications, it does not need to submit the “Declaration of Commencement of Electronic Issuance of Documents.”

What the Regulatory Framework Provided

Under Decisions A.1128/2025 and A.1129/2025, the declaration was introduced for two main purposes.

The first concerned incentives for the early adoption of electronic invoicing, pursuant to Article 71Θ, paragraph 1 of the Income Tax Code, during the period in which the relevant incentives were in force.

The second concerns the possibility of gradual compliance by obliged entities, while continuing to use the existing methods of issuing tax documents.

As of October 1, 2026, the second provision becomes particularly relevant for businesses that fall within the €1 million revenue threshold and wish to make use of the transitional period through the end of the year.

Separate Declaration for Electronic Invoicing Service Providers

AADE also clarifies that the above guidance applies exclusively to the declaration concerning the use of the timologio or myDATAapp applications.

The requirements for submitting a declaration regarding the use of Electronic Invoicing Provider Services, as provided for under AADE Governor’s Decision A.1112/2025, are not affected by these provisions.

These are therefore separate procedures and should not be confused by businesses.

No Changes to Retail Transactions

A separate clarification concerns transactions with final consumers.

The introduction of mandatory electronic invoicing does not alter existing obligations or the way revenue documents are issued in retail transactions.

The new requirements therefore concern electronic invoicing for transactions falling within the relevant framework and do not change the way tax documents are issued for transactions with private individuals.

Where the Declaration Is Filed

Businesses required to submit the “Declaration of Commencement of Electronic Issuance of Documents” must complete the process electronically through the myAADE digital portal.

The relevant pathway is:

myAADE → Applications → Tax Services → myDATA → Declaration of electronic issuance of documents through a Provider, Self-Provider or the timologio application.

The deadline for businesses opting for the adjustment period is October 12, 2026.

Key Takeaways for Businesses

The key point in AADE’s clarification is that not all businesses subject to mandatory electronic invoicing are required to submit this particular declaration.

From October 1, the obligation applies to businesses with gross revenues of up to €1 million in 2023 that choose to make use of the transitional period through December 31, 2026, while continuing to use the existing methods of issuing invoices in parallel.

By contrast, businesses that issue all their invoices exclusively through timologio or myDATAapp as of October 1 are not required to submit the declaration.