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Andres Lilleste’s name is familiar to everyone in the Estonian e-invoicing landscape as one of the pioneers and advocates of e-invoicing in Estonia. With 20 years of experience in e-invoicing at Unifiedpost and his recent role as the Lead of the Compliance Cluster, ensuring that our clients’ invoicing operations worldwide meet regulatory standards, there is no doubt that Andres knows everything about e-invoices and, fortunately for us, he’s happy to share his thoughts.
You’ve been involved with e-invoicing from the very beginning. Tell us how you got into this field and when did you realize that e-invoices were the future?
For me, the word “beginning” has two meanings. First, I started working in 2005 as a technical customer manager in the e-invoicing field. My first day on the job was immediately related to e-invoices. Secondly, it was around the time when e-invoicing was starting to take off in Estonia. The e-invoicing service in banks had just been launched, allowing e-invoices to be sent to customers’ banks, and automatic payment agreements could be set up, but B2B and B2G e-invoices hadn’t yet been introduced. We looked at what our northern neighbours were doing and tried to figure out how to get e-invoices moving between businesses. It took two years, but we managed to launch the first B2B (expense) e-invoices.
If you had to explain e-invoicing to your grandmother or to high school students, how would you describe it in simple terms?
For an ordinary person, whether young or old, the simplest way to explain e-invoices is through the convenient ability to automatically pay an invoice. If you get an invoice on paper or as a PDF, it’s nice to look at, but what next?! When you receive an e-invoice, your payment form in the bank is already filled in. For businesses, there are many other benefits as well, like eliminating the need for manual work.
There must have been some colourful situations in your work related to this topic?
When I think of real-life examples (and big joy), I recall the time before 2010 when we worked hard to introduce e-invoices to consumers and businesses. We ran campaigns where we planted one tree for every e-invoice sent. The results were nice, but far from today’s levels.
I also remember a lottery where we gave away the prize of three months of e-invoice payments on our behalf, drawn among e-invoice users. The e-invoice consumption kept growing, and the winner happened to be someone with a combine leasing invoice, with many other e-invoices flowing into their account. Fortunately, we had set a maximum amount in our campaign to be reimbursed.
What’s the most common misconception about e-invoices that you encounter in your work?
I feel that these misconceptions change over time. The original challenge was to explain that a PDF invoice (a paperless invoice) is not an e-invoice. Unfortunately, this opinion dominated for a long time. There have also been opinions that e-invoicing creates a risk that someone can track your deliveries and the sensitive information appearing on the invoice. But I believe that today, these are mostly things of the past. Today’s consumer tends to make rational calculations and tries to find the most economically optimal way to use e-invoicing.
Unifiedpost Group is represented in over 30 countries and continuously monitors e-invoicing legislation. How do you ensure that businesses don’t have to worry about regulations?
I am convinced that to gain the trust of our customers, we must be ready to educate and support them – both in the sales process and in post-sales services. A client wants to feel cared for and kept up to date with trends and changes. Clients generally don’t want to know all the technical details. They want the principles.
To provide this supportive environment for our clients, Unifiedpost created a separate unit a few years ago – the "Compliance Cluster". This team consists of specialists who work daily on gathering and analysing information, and setting development tasks within the company to ensure that Unifiedpost’s products comply with e-invoicing regulations.
I have used this comparison before, but now, with the true diversity of e-invoicing regulations worldwide, it is more relevant than ever – one partner, all services. The client focuses on growing their business, and we do our best to ensure that their invoices are sent and received in full compliance with all requirements.
The Current State and Future of E-Invoicing Worldwide
Which countries are currently at the forefront of e-invoicing? Is there something other countries can learn from them?
I believe this is a question where the answer depends on which region the expert is from. We see countries that strongly support centralization and regulations, countries that offer a "variety" of solutions – where standard transmission and alternatives are allowed simultaneously, and then there are countries where everything works more or less spontaneously but technically at a very high level.
The role of a country’s VAT loss over the course of the year certainly also plays a part. A dominant phrase in regulations is that “the e-invoice must meet EN16931 standards”. EN16931 is the technical name for the EU e-invoice standard. We also often see references to Peppol transmission. Peppol has grown into a global network for e-invoice transmission. A third thing we see is references to e-reporting. This is a situation where the local tax authority expects real-time or near real-time tax declarations from invoicers.
Looking at all of the above, Italy is currently at the forefront of e-invoicing in Europe, having strongly advocated for all e-invoices to go through the country’s central platform. France is launching an e-invoicing solution based on the Peppol architecture in the second half of 2026, where the tax authority is one of the parties, and VAT is taken on the invoice almost in real-time.
Belgium, Germany, Latvia – starting from early 2026, B2B e-invoice requirements will come into effect, combined with Peppol or, if absent, an alternative e-invoice channel.
As an Estonian, I like the Nordic approach where e-invoicing between businesses is voluntary but very widespread and a normal part of doing business. The e-invoice is the standard. Unfortunately, voluntary adoption has not yet brought widespread use of e-invoices in Estonia. I believe the ViDA (VAT in Digital Age) directive will bring changes in tax declarations, where e-invoice will be one of the ways to transmit information.
Which countries will soon make e-invoicing mandatory? How will this affect businesses that want to operate internationally?
Increasingly, we see that international companies are looking for service providers to help them understand requirements and also implement invoice transmission solutions. It’s overwhelming to follow all of these changes and keep up with continuous technology updates. In addition, there are quite a few changes in deadlines. There are usually delays but following them is also a challenge.
Starting from January 2025, B2G e-invoicing obligations will apply in Germany and Latvia. In the near future, regulations will change in countries such as Greece, where B2B e-invoicing will become mandatory from July. In January 2026, a series of changes are coming: B2B e-invoicing in Belgium and Latvia, the repeatedly postponed B2B regulation in Poland, and Croatia will join with B2B e-invoicing. By 2027, Slovakia and Slovenia are expected to implement their own changes.
How much do e-invoicing requirements differ between countries? Are some countries particularly complex or unexpected?
The most complex requirements are in countries that started their e-invoicing projects before the ViDA initiative was developed. ViDA brings rules for cross-border tax reporting but also provides clear recommendations for technical solutions – e-invoicing via EN16931 and e-invoice transmission via the Peppol network.
Estonia and the Development of E-Invoices
Estonia was one of the first countries where sending e-invoices became mandatory for the public sector. How has this affected businesses' attitudes toward e-invoicing?
The obligation to send e-invoices to the public sector came into effect on July 1, 2019. The only way to receive payment for services provided to the state was through submitting an e-invoice. This change quickly brought B2G e-invoicing to its maximum level. Only cross-border suppliers were still allowed to submit invoices in PDF format.
There was also an impact on the growth of B2B e-invoices, but to be honest, I believe everyone working with e-invoices on a daily basis was expecting a bit more rapid growth. A positive trend we saw was the exchange of ideas about new technical possibilities, and this period also marked the launch of real-time economy (RTE) projects in Estonia. Estonia provides a great environment for testing and launching new ideas, supported by flexible legislation and a strong e-government.
When comparing Estonia to its neighbouring countries and Europe, are you more innovators or more conservative in terms of e-invoicing?
My answer would be conservative innovators. In a good technological environment where the state has led by example with B2G e-invoices, B2B e-invoicing is growing slowly but steadily through voluntary submissions. A good example of our technological background is the Business Register, which serves as our central address book and shows whether a company is an e-invoicing entity or not.
Are Estonian companies generally well-prepared for the adoption of e-invoices, or is there still room for improvement? Which sectors are the most advanced, and which are lagging behind?
The transition to e-invoicing is easier for medium and large companies. This is due to two reasons: they typically already use accounting software that supports e-invoicing, and secondly, they have more to gain from making their invoicing processes more efficient. E-invoices facilitate faster information flow, the invoice lifecycle is traceable from start to finish, and payments and archiving can all be done with a single click.
However, companies that don’t use accounting software (micro-enterprises) or have not yet activated the e-invoicing integration in their existing software should focus on changing their work methods. For the latter, we still need to work on a trend where sending PDF invoices by email is considered an acceptable form of invoicing. It’s important to remember that emails tend to get lost, data from PDFs has to be manually entered, and this can lead to data entry errors.
What can Estonian entrepreneurs and accountants do today to be more aware of e-invoicing and be ready for the future?
I have three recommendations here: 1) If you’re not using accounting software yet, start using it or a cloud-based invoicing service that helps organize data and provides a clearer overview; 2) If you already have a software solution, feel free to contact your service provider’s customer support and ask about e-invoices – both for sales and purchase; 3) If you need more from your existing software (volume, cross-border transactions, other regulations), feel free to contact e-invoice operators and find a reliable partner who can help solve these issues.
In Estonia, there is still a widespread belief that an e-invoice is simply sending a PDF by email. How can we break this belief?
I don’t want to scare anyone, but based on our experience, PDFs as email attachments are associated with three main risks: 1) They tend to get lost; 2) Errors occur when manually entering data from PDFs (both parties lose time and energy dealing with errors); and 3) Fraudulent emails are common in our region – unfortunately, this trend is also growing in the case of invoices. We always hope for the best, but to minimize risks, the safer approach is to choose the e-invoicing path. An e-invoice operator ensures that there are no unknown senders or receivers in their network, the data is verified, and the entire invoice lifecycle is traceable (both positive and negative events are mapped).
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