Mandatory electronic invoicing!

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Electronic Invoicing became mandatory in Public Administration in 2021

In January 2021, electronic invoicing became mandatory for public procurement, in accordance with the European Directive 2014/55/EU.

According to the recent changes introduced by the Decree-Law No. 14-A/2020 of 7 April, within the scope of the exceptional measures approved in the context of the COVID-19 pandemic, the deadlines established by article 2 of the Decree-Law No. 123/2018 of 28 December were altered, defining its compulsory adoption until the 31st of December 2020 for large companies, until the 30th of June 2021 for small and medium-sized companies and, until 31st of December 2021 for micro-companies.

Electronic Invoicing has new rules

The Decree-Law No. 28/2019 of 15 February regulates several aspects about the issuance of invoices, including electronic invoicing.


An electronic invoice is a document identical to the traditional paper invoice, maintaining an identical legal value, but with an entirely digital life cycle: the issuing, sending, receipt and storage of invoices takes place solely by electronic means. The authenticity of the origin and the integrity of the electronic invoice content must be guaranteed using a Qualified Electronic Seal, in case of legal entities, and a Qualified Electronic Signature, in case of individuals.

Decree-Law No. 28/2019

Change in the type of digital certificate to be used: qualified electronic seal or qualified electronic signature.

Decree-Law No. 123 / 2018

of 28 December, as amended by Decree-Law No. 14-A / 2020

31 DECEMBER 2020

Large companies:

+250 employees

> 50,000,000 turnover

> 43,000,000 balance sheet

30 JUNE 2020

Small and medium-sized companies

31 DECEMBER 2021



Choose a solution suitable to your needs!

HSM Cloud Qualified Certificate for
Electronic Invoicing

Legislation now requires all electronic invoices to be signed with a Qualified Digital Certificate (Qualified Electronic Seal), invalidating the use of the Advanced Certificate, in force until then.

Certificate valid for 12 Months

Complete Eletronic
Invoicing Solution

If your invoicing software is not yet integrated with DigitalSign Certification Authority, you can use the DS Invoice application, which guarantees full compliance with the applicable legislation, to sign and send your invoices to your customers.

Includes Certificate valid for 12 Months

* To all mounts must be added the VAT at the tax rate in force


The main advantages of acquiring a Qualified Seal for documents and Electronic Invoicing


Guarantees the identity of the entity issuing the electronic invoice.


Allows the detection of any changes made to the electronic invoice’s content.


Guarantees the existence of secure mechanisms on the creation of electronic invoices, which allows its control.


Get to know the recent legal developments applicable to Electronic Invoicing

See here our press release on the subject and consult below the documents issued by the Portuguese Tax Authority and the National Security Office (GNS).

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We prepared some answers for you ...

An invoice is a commercial document whose issuance is generally mandatory for all transmitters of goods, or services providers, being an essential element for the Value Added Tax (VAT), which gives purchasers of goods or recipients of services a credit before the State, which is embodied in the exercise of the right to deduct the tax incorporated therein.

The electronic invoice is the same commercial document, but reduced to an electronic format, that is, ‘dematerialized’. The electronic invoice has the same legal value as the paper invoice, as long as it contains the mandatory information for any invoice and meets the conditions required by law, to guarantee the authenticity of its origin and the integrity of its content.

No. It is already possible to adopt electronic invoicing, containing the applicable legislation to all elements necessary for its rightful adoption.

Yes. The deadline initially foreseen for the mandatory adoption of electronic invoicing in public procurement was the 1st of January 2019, however the recently published Decree-Law No. 123/2018. which defines the governance model for the implementation of electronic invoicing in public contracts and, among others, established alternative deadlines for mandatory electronic invoicing, in the scope of public contracts, in which electronic invoicing became mandatory only from the 18th April 18, 2019, for direct government agencies and public institutes. This deadline was extended until April 2020 for the remaining public bodies and for large companies, with SMEs benefiting from an extension of the deadline until 31 December 2020

It is important to emphasize that some essential aspects of the electronic invoice regime are already regulated both in the VAT Code (Art. 36, no. 10) and in Decree-Law No. 196/2007, however, others, such as the format of the file to be used is expected to be defined through an ordinance, to be published until the entry into force of the mandatory electronic billing in public procurement.

The law clearly states its equivalence to the paper invoice, provided that the general requirements to which any invoice must comply with are met, plus the specific requirements for the electronic invoice.

There are two different types of electronic invoicing: invoices with structured format and unstructured format.

Those issued in a structured format file allow automatic processing by computer systems, but are not readable by the human eye, being the most common example the XML format, which is the typology adopted in the scope of public procurement.

Those issued in an unstructured file are created through a non-automated process and involve the use of optical character recognition technology (OCR). This is the case of invoices issued in PDF file, which are generally adopted within the scope of the private sector invoicing and for the final customer.

Yes. In general terms, taxpayers can electronically issue invoices or equivalent documents, as long as the authenticity of their origin and the integrity of their content are guaranteed through an advanced electronic signature or electronic data interchange (EDI).

A different situation results from the transposition of the Directive 2014/55/EU, through the Decree-Law No. 111-B / 2017, of 31 August, which amended the Public Contracts Code (CCP), considering that the issuance of electronic invoices in the scope of public procurement will become mandatory, in accordance with the deadlines indicated in point 2.

There is some tendency to confuse the electronic means of transmission used, with the form of the documents transmitted.

Provided that the authenticity of its origin and the integrity of its content are guaranteed by means of an advanced electronic signature or advanced electronic seal pursuant to Regulation (EU) No. 910/2014 of the European Parliament and of the Council of 23 July 2014 or electronic data interchange (EDI), as defined in the Commission Recommendation 1994/820/ EC, of 19 October 1994, any available electronic means of transmission can be used.

Yes, as long as long as the electronic invoice contains an advanced electronic signature, and as long as the issuing entity is not obliged to use any specific platform such as the Electronic Invoice Portal in the Public Administration of ESPAP (mandatory for the entities provided for in paragraph 3 of Decree-Law No. 123/2018). However, it should be made clear that the entry of data in the body of the e-mail message is not accepted as an electronic invoice under the terms of the law.

In the scope of public procurement, the form of electronic invoicing should take place through a structured file, allowing the automation of the entire process. The format of this file will be defined through a ministerial directive, in accordance with paragraph 5 of article 299-B of the Decree-Law No. 111-B / 2017 of 31 August, but it still awaits publication, if, however, the UBL V2.1 format is adopted, according to the European standard EN 16931-2017. For more technical information on the format to be adopted, you can consult the following document, published by ESPAP:

In electronic invoicing, for the private sector, there is no obligation to use a specific format as long as its authenticity and integrity are guaranteed.

No. The only two ways of issuing electronic invoices are those in which the authenticity of their origin and the integrity of their content are guaranteed, either by affixing an advanced electronic signature or in which these guarantees are assured by electronic data interchange, commonly referred to by the acronym EDI.

In Portugal, the digital certificate legally required for electronic invoicing is the advanced digital certificate. This certificate must be issued by a certifying body duly accredited with the National Security Office (GNS), as is the case with DigitalSign. For more information on the topic, consult the Communications Guide for the Transmission of Electronic Invoices to the PA, starting on page 5.

The digital certificate used to sign must be issued under the name of the entity issuing the invoices, that is, the taxable person. The purpose of using the certificate is to uniquely identify the issuer of electronic invoices.

Electronic invoices issued by one entity and signed by another legally distinct is not accepted by the Tax Authority, as it does not comply with the applicable law. This way, the aim is to guarantee the principle of authenticity of invoices and the issuer's responsibility, safeguarding that the entity signing the invoices is their author.

In this sense, if you use an electronic invoicing platform, always require that your invoices are signed with a digital certificate issued on behalf of your company.

It depends on the applicable legal requirements. In Spain, for example, the law imposes the obligation to use a qualified certificate to sign electronic invoices.

Thinking about its customers and considering this reality, DigitalSign is preparing the launch of a new product: the qualified digital certificate stored in software for electronic invoicing.

Yes, as long as the certificate has no limitations on the scope of its use. It is also important to bear in mind that if you use a digital electronic seal certificate, intended exclusively for legal persons, you benefit from the fact that no personal data is shared, only the data of the organization.

Taxpayers who electronically issue or receive invoices or equivalent documents must keep them on paper and in lists identifying them, for each tax period (monthly or quarterly), and these lists must contain, in particular, the identification of the invoices (numbers and date), the identification and TIN (tax identification number) of the issuer and receiver, the amount of VAT paid and the total amount of the invoice (art. 45 and art. 48 of CIVA).

In accordance with the provisions of paragraph 4 of article 52 of CIVA, invoices or equivalent documents electronically issued and received must be filed in electronic form, provided that the Tax Administration is guaranteed full access and in line to the data and the integrity of the source and content is ensured.

Taxpayers are required, pursuant to paragraph 1 of article 52 of the VAT Code, to file and keep in good order for the subsequent 10 years, all invoices or equivalent documents issued and received in electronic format. Mandatory filing can be done by the service provider itself or under the provision of services by third parties in the name and on behalf of the taxable person.

Certainly! This type of process depends, above all, on two factors: market adhesion and inter-company business rules. Coexistence between the electronic invoice and the paper invoice is inevitable.

Yes, the Law allows the operation of the computer system or the data storage to take place outside the country. In this case, the taxable person being inspected must provide the Portuguese tax administration access from the national territory and ensure the necessary support, namely through the instruction on the procedures to be adopted to access the invoicing support computer system and to consult the data stored.

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