DESAmedia ·

The short answer

If you invoice a ministry, a municipality, a hospital, a school or any other contracting authority in Lithuania, e-invoicing is already mandatory for you. Since 1 July 2024, those invoices must follow the European e-invoicing standard (EN 16931) and go through SABIS, the state invoice platform. Invoices between businesses (B2B) can still be sent as PDFs or on paper, and a structured e-invoice is used only when the buyer agrees to it. The European Commission's country sheet mentions 1 January 2028 as a target for mandatory e-invoicing, but as of this writing (22 October 2026) we could not find any adopted Lithuanian law that sets it. The firm EU-wide date is 1 July 2030, when the ViDA directive's digital reporting rules start for cross-border B2B transactions.

In practice: if you sell to the public sector, automate SABIS now. If you don't, this is a good moment to clean up invoice data in your CRM, ERP or online store, so that connecting to Peppol or any future mandate becomes an integration task rather than a rebuild.

Three different things: i.SAF, SABIS and Peppol

These terms get mixed up all the time, but they solve different problems.

What it is Who must use it What gets sent
i.SAF A subsystem of the tax authority's (VMI) i.MAS platform for VAT invoice registers VAT payers registered in Lithuania (except those under the small business scheme) Monthly registers of issued and received invoices; companies file by the 20th of the following month
SABIS The national invoice administration system, run by the National Shared Services Centre (NBFC) Suppliers invoicing public sector bodies and contracting authorities Each invoice individually, in an EN 16931 compliant format
Peppol An international network for exchanging e-documents through certified access points Not mandatory in Lithuania on its own E-invoices and other documents between connected organisations

i.SAF is not e-invoicing. It's a monthly list of your invoices for the tax authority. The buyer still receives the invoice separately, by email, on paper or through SABIS. VMI accepts the data as an uploaded XML file, through a web service, or entered by hand.

SABIS is the mandatory channel for the public sector. It replaced the older "E. sąskaita" system in 2024. The transition ran until 31 August 2024, and SABIS has been fully live since 1 September 2024. It isn't used for invoices to private buyers.

Peppol is a delivery route. If your system is connected to Peppol through an access point provider, you can deliver invoices to SABIS that way. The same connection later works for customers in other countries who use Peppol.

What is already mandatory

Lithuania has required electronic invoices in public procurement since 1 July 2017. Since 1 July 2024, under a Government resolution, invoices to public sector bodies and other contracting authorities must be submitted through SABIS.

A few practical details suppliers often miss:

  • Invoices under verbal contracts. When SABIS launched, invoices under verbal (unwritten) contracts above EUR 1,000 excluding VAT had to go through it. Since 1 January 2025, all of them do, whatever the amount. So even a small one-off order from a municipal agency goes through SABIS.
  • The link to a contract. SABIS ties invoices to contracts. Buyers review their public procurement contracts in the system and register contracts concluded outside procurement. If your system doesn't know which contract an invoice belongs to, automated submission will stall.
  • Format. According to the European Commission, SABIS is connected to Peppol and supports the Peppol BIS Billing 3.0 and CII formats.

Three ways to submit an invoice to SABIS

NBFC lists three channels:

  1. The SABIS portal. You type the invoice in by hand. Fine if you send a handful of public sector invoices a month.
  2. The Peppol network. The invoice travels from your system through a Peppol access point provider. Makes sense if you already use Peppol or send e-invoices abroad.
  3. The universal invoice data interface. A direct integration with the SABIS API. NBFC's specification says it uses OAuth 2.0 for authentication, access tokens are valid for 5 minutes, and the methods are described in OpenAPI format.

One warning NBFC made explicitly: suppliers that send invoices automatically from their business systems had to update their integrations to the new specification. An integration built for the old "E. sąskaita" system doesn't work with SABIS.

B2B invoices: what applies now and what's coming

Now. VMI explains that an electronic VAT invoice may be used only with the buyer's prior consent, which can be given in any form. A PDF sent by email also counts as an electronic invoice. So a structured format isn't required for B2B invoices yet.

2028. The European Commission's 2025 eInvoicing Country Sheet for Lithuania says mandatory e-invoicing is targeted for 1 January 2028. The same sheet lists the B2B mandate as "No", and we couldn't find an adopted law or a bill before the Seimas. Treat it as a scenario to plan for, not a deadline, and watch announcements from VMI and the Ministry of Finance.

2030. Council Directive (EU) 2025/516, known as ViDA, was adopted on 11 March 2025 and entered into force on 14 April 2025. Since then, member states can introduce mandatory e-invoicing without asking the EU for a derogation. From 1 July 2030, digital reporting requirements apply to cross-border B2B transactions within the EU: data on each transaction, with e-invoices that in principle follow the EN 16931 standard. If you sell to companies in other EU countries, this date will affect you regardless of what Lithuania decides.

What to prepare in your CRM, ERP or online store

Many Lithuanian companies issue invoices from more than one place: some from the accounting software, some from the CRM, some from the online store, and some from an Excel template. That's tolerable while invoices are PDFs. Once an invoice becomes a structured document checked by a machine, every missing field means a rejected invoice and a late payment.

1. The invoice data model

EN 16931 defines which fields an invoice must contain and how they relate. The gaps we see most often:

  • buyer identifiers (company code, VAT number) stored as separate fields rather than as text inside the address;
  • the contract or purchase order number the buyer uses to match the invoice;
  • a VAT category on every line, and the exemption reason when VAT isn't charged (Lithuanian VAT law already requires that reference today);
  • unit codes instead of free text like "pcs" or "hrs";
  • consistent rounding, so line totals and the invoice total match to the cent.

If your system already stores this data in structured form, generating the format is the easy part. If it lives in free text, the work starts with the data, not the format.

2. One sending layer, not one per system

A common mistake is building one SABIS connection in the CRM, another in the online store and a third in the accounting software. It's more reliable to have a single invoice sending module: every system hands it the invoice data, and the module decides where it goes. Public sector buyers get it through SABIS, foreign buyers through Peppol, everyone else as a PDF by email. When a new mandate appears, you change one module.

3. Statuses, errors and retries

An e-invoice isn't "send and forget". Your system needs to know whether each invoice was accepted, rejected or is waiting for the buyer, and show that to the accountant or account manager. The minimum:

  • a status for every invoice with date and time;
  • the rejection reason in plain language;
  • automatic retries when a channel is temporarily down, with a clear limit on when retries stop;
  • an audit log of who changed or resent what, and when.

4. Credit notes and corrections

Cancellations, credit notes and corrections must be linked to the original invoice. SABIS training materials treat credit notes as a separate function, so your system should generate them through the same route, not by hand in the portal.

5. Incoming invoices

The other side: if you are a contracting authority, or suppliers send you e-invoices, it pays to receive them straight into your own system. A structured invoice can be matched automatically against the order and the goods receipt instead of being retyped from a PDF.

An example of how this works

The company below is fictional, and the details are for illustration only.

Baltų įranga UAB sells laboratory equipment. About a third of its customers are hospitals and universities; the rest are private companies in Lithuania and Latvia. Invoices come out of the accounting software, orders live in the CRM, and the service team writes its invoices in Excel.

Every week, the accountant types the public sector invoices into the SABIS portal by hand. Now and then an invoice is rejected because the contract number is wrong, and nobody notices until the buyer pays late.

The fix wasn't new accounting software but an invoice sending module between the existing systems:

  1. CRM orders for public sector customers got a mandatory contract number field.
  2. Service invoices moved out of Excel into the same system as sales.
  3. The module sends public sector invoices through the SABIS universal interface and everything else as PDFs by email, and statuses flow back into the CRM.
  4. A rejected invoice creates a task for the responsible account manager, with the reason attached.

When Latvian customers start asking for e-invoices, or the company joins Peppol, that's one more channel in the same module.

Common mistakes

  • Treating i.SAF as an e-invoicing solution. i.SAF registers never deliver an invoice to the buyer.
  • Waiting for 2028. That date isn't confirmed, and SABIS is mandatory today. If a B2B mandate does come, the work is the same: data model, sending layer, statuses.
  • Integrating every system separately. Three connections mean three places for things to break, and three times the work when requirements change.
  • Ignoring rejections. Without automated error handling, you learn about problems from the overdue payments report.
  • Forgetting small verbal contracts. Since 2025, all of their invoices go through SABIS, whatever the amount.

FAQ

Do I have to use SABIS if I only send a few invoices a year to the public sector?

Yes. Everyone who serves public sector bodies or contracting authorities must submit invoices through SABIS, regardless of volume. At low volumes the SABIS portal is enough; an integration pays off as the volume grows.

Is a PDF invoice sent by email an e-invoice?

For VAT purposes, yes: VMI treats it as an electronic VAT invoice if the buyer agreed to receive it. But in the SABIS and ViDA sense, an e-invoice is a structured EN 16931 document that a machine can process, and a PDF isn't one.

Do we have to connect to Peppol?

No. Peppol is one of three ways to submit invoices to SABIS. It's useful if you send e-invoices to other EU countries or want one connection for many recipients.

How much does a SABIS integration cost?

It depends on how many systems issue invoices and how clean their data is. Integrating one system with tidy data is a small project. If invoice data first needs cleaning up across several systems, that's where most of the effort goes. We covered the general pricing logic in our article on what custom software development costs.

Will B2B e-invoicing become mandatory in 2028?

That isn't confirmed. The European Commission's country sheet mentions a 2028 target, but we found no adopted Lithuanian law. The firm date under EU law is 1 July 2030, for cross-border transactions.

What to do next

Start with an inventory: which systems issue invoices, how many go to the public sector, and which fields are stored in structured form. If invoices come from several places, sort out the data first, then build a single sending layer. We wrote more about connecting accounting software to other systems in integrating Rivilė, Directo and Agnum, and if invoices still start life in spreadsheets, have a look at 7 signs your business has outgrown Excel.

DESAmedia builds integrations between CRMs, ERPs, online stores and accounting software, including invoice submission through the SABIS interface, status tracking and error handling. You'll find more on our integrations and automation page, and public sector organisations may want to see our public sector page. If you'd like to talk through your setup, get in touch.

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