Your group has subsidiaries in Tallinn, Riga, Vilnius and Bratislava. Your IT team has mapped your domestic e-invoicing obligations and your Peppol rollout. But while that work has been underway, four countries in Northern and Central-Eastern Europe have been building their own e-invoicing mandate timelines — with distinct dates, formats and technical architectures that are not covered by your domestic deployment.
This guide covers the regulatory obligations in force and upcoming in each of these four countries, along with the concrete actions required on the ERP side.
Why these four countries are ahead on digital tax compliance
The “e-Estonia” brand is not a marketing slogan. The X-Road platform, operational since 2001, interconnects more than 900 Estonian public services through an interoperable data network: tax declarations, notarial acts, medical prescriptions, electronic voting. This infrastructure made B2G e-invoicing a natural step: Estonia has required structured invoices from public-sector suppliers since 2019 (EMTA, Estonian Tax and Customs Board).
Latvia and Lithuania followed a similar trajectory, driven by adoption of the Peppol network as a common interoperability standard. Slovakia, for its part, built its digital maturity on the eKasa system (B2C transaction dematerialisation since 2019), which served as a proving ground before the leap to mandatory B2B e-invoicing.
By 2026, all four countries have operational B2G mandates and firm B2B timelines. For a multinational group with subsidiaries in these countries, the question is no longer “whether” but “by when” the ERP must be compliant.
Estonia: “buyer-choice” model since July 2025, universal mandate in preparation
What is already in force
B2G e-invoicing has been mandatory in Estonia since 2019 for all public-sector suppliers. The Accounting Act, amended in September 2024, introduced a “buyer-choice” mechanism from 1 July 2025: any company registered as an e-invoice recipient in the Estonian Business Register can require its suppliers to transmit invoices in a structured format compliant with the EN 16931 standard (EDICOM, Estonia e-invoicing B2B law).
In practice, a growing number of major Estonian buyers have activated this right. For subsidiaries of European groups supplying these companies, the mandate is already effectively operational — even if not yet universal.
What this means for your ERP
Estonia operates a decentralised model: there is no state-run national platform for B2B. Invoices flow through certified service providers (Telema, Finbite, Unifiedpost) that are interconnected with each other and via the Peppol network. The Estonian subsidiary must therefore be connected to one of these operators, capable of sending and receiving invoices in Peppol BIS Billing 3.0 or EVS 923 format (the Estonian national XML format, still accepted by mutual agreement between parties) (VATCalc, Estonia e-invoicing).
Horizon 2027
The Estonian tax authority EMTA and the Ministry of Finance have published a roadmap pointing towards a universal B2B mandate. The year 2027 is regularly cited in preparatory working documents (Storecove, Estonia e-invoicing guide), but had not been confirmed by definitive legislation at the time of publication. The direction of travel is clear: companies that connect now are getting ahead of the curve.
Latvia: B2G mandatory since January 2026, B2B mandate set for 1 January 2028
What has been in force since 1 January 2026
Latvia made e-invoicing mandatory for G2G, B2G and G2B flows from 1 January 2026. Invoices must be transmitted in Peppol BIS Billing 3.0 (XML) format via the national Peppol network operated by VRAA (Valsts reģionālās attīstības aģentūra) or a certified Access Point (EDICOM, Latvia e-invoicing postponed to 2028).
Latvia has adopted a “5 corners” model with Continuous Transaction Controls (CTC): the data from each invoice must be transmitted to VID (Valsts ieņēmumu dienests, the State Revenue Service) within 5 business days of issuance. This reporting flow is separate from the transmission flow to the recipient.
B2B: voluntary since March 2026, mandatory from 1 January 2028
The original calendar had envisaged a B2B mandate from 1 January 2026. The Latvian Parliament pushed this deadline back to January 2028 through amendments adopted in June 2025 (Taxilla, Latvia B2B postponed to 2028). Since 30 March 2026, companies can voluntarily participate in the B2B system via the eAddress platform.
The practical implication: if your Latvian subsidiary issues invoices to private Latvian companies, it is not yet required to go through Peppol. But it can do so today, and some major Latvian buyers are already contractually requiring structured invoicing.
One specific point to watch: unlike Estonia, Latvia imposes a reporting obligation to VID within 5 business days. Your Access Point must handle this separate flow, or your ERP must send the data directly via the VID API.
Lithuania: B2G via SABIS since 2024, B2B targeted for 2028
SABIS: the B2G platform operational since September 2024
Lithuania restructured its public-sector e-invoicing system in September 2024 with the launch of SABIS, the successor to the former E. sąskaita portal. Since 1 January 2025, all invoices issued to Lithuanian public institutions must go through SABIS, with no threshold exemptions (bilnex, Lithuania e-invoicing 2027). The required format is Peppol BIS Billing 3.0.
An important point for multinational groups: companies not established in Lithuania cannot access the SABIS portal directly. They must use the Peppol network. If your group invoices Lithuanian public entities from a foreign legal entity, you must have a Peppol Access Point connected to the Lithuanian network.
B2B: no confirmed legal date, a 2028 target aligned with ViDA
There is currently no legal B2B e-invoicing mandate in Lithuania (ecosio, Lithuania e-invoicing compliance). The tax authority VMI (Valstybinė mokesčių inspekcija) has begun preparatory work aligned with the ViDA roadmap, targeting a B2B rollout around 1 January 2028, but no legislation has yet confirmed this date. The Lithuanian Parliament has 26 months to legislate before the ViDA 2030 deadline on cross-border transactions.
Slovakia: B2B mandatory from 1 January 2027
The most precise mandate timeline in the region
Slovakia is the only one of the four countries to have enacted a B2B mandate with a firm legal date before 2028. Law No. 385/2025 Coll., passed by the Slovak Parliament on 9 December 2025, requires structured e-invoicing for all Slovak VAT-registered businesses for domestic B2B transactions from 1 January 2027 (KPMG, Slovakia VAT e-invoicing 2027). Legal entities not registered for VAT must be capable of receiving e-invoices from the same date.
The extension to intra-EU cross-border B2B transactions is planned for 1 July 2030, in line with the ViDA calendar.
The 2026 preparatory phase
The Finančná správa (Slovak tax authority) published in March 2026 the list of certified providers for e-invoice transmission — the “digital postmen” of the Slovak Peppol network (VATUpdate, Slovakia certified providers March 2026). Since May 2026, companies can voluntarily participate in the system and issue eFaktúra e-invoices already recognised as valid fiscal documents.
Format and technical architecture
Slovakia has opted for the decentralised Peppol network, with the Peppol BIS Billing 3.0 (UBL 2.1) profile and a national CIUS (Custom Implementation Usage Specification). Every Slovak subsidiary will need to select a Peppol provider certified by the Finančná správa: the updated list distinguishes providers still in accreditation from those that are fully certified.
How to adapt your ERP for these four countries
The Peppol connector: the common denominator
All four countries share a common standard: Peppol BIS Billing 3.0. This is what makes multi-country compliance technically feasible without a complete overhaul of the central ERP. The principle: a certified Peppol Access Point acts as the intermediary between your ERP and the national networks. Your ERP sends a structured invoice to your Access Point; it then routes it to the correct Peppol network for the destination country.
Pan-European operators covering all four countries include: Pagero, Sovos, Avalara, Storecove, OpusCapita and Ecosio. Verify that your contract explicitly covers Estonia, Latvia, Lithuania and Slovakia — national CIUS requirements vary, and the Latvian CTC mandate requires an additional reporting flow.
Native ERP capabilities
- SAP: SAP Document and Reporting Compliance (DRC) covers the Baltic States and Slovakia. Check the version of the localisation module and the country-specific SAP Notes.
- Oracle Fusion / NetSuite: Oracle Tax Reporting Cloud with Peppol connector. Baltic localisations are available but may require a configuration update.
- Odoo 17+: native Peppol module with integrated SMP, configurable per country. The Slovak CIUS is supported from version 17.1.
- Sage X3: no native Peppol connector for the Baltic States; a third-party Peppol middleware is recommended (Pagero, Sovos).
Key points to watch
Local VAT numbers: verify that your ERP handles the EE (Estonia), LV (Latvia), LT (Lithuania) and SK (Slovakia) prefixes. A misconfigured field causes automatic rejections at XML schema validation.
Language requirements for legal mentions: for Lithuania, invoices addressed to public entities must include legal mentions in Lithuanian. The other three countries do not impose a local language requirement for structured B2B invoices.
Electronic archiving: a minimum of 7 years in all four countries. Your electronic archiving must meet integrity and long-term readability requirements, in compliance with eIDAS 2.0 for electronic signatures.
Latvian CTC reporting: Latvia requires invoice data to be reported to VID within 5 business days of issuance. This flow is separate from the delivery flow to the recipient. Your Access Point must handle it, or your ERP must transmit the data directly via the VID API.
CIO Checklist: six actions before end of 2026
- Inventory your in-scope subsidiaries: which entities are established in Estonia, Latvia, Lithuania or Slovakia? What is their current ERP setup (local, regional or group instance)?
- Prioritise Slovakia (deadline: 1 January 2027): this is the closest firm deadline. Launch a pilot with 3 to 5 Slovak suppliers or customers before end of Q4 2026, using the voluntary phase already open.
- Verify your Access Point’s Peppol coverage: does your operator cover all four countries? Which national CIUS specifications? Is it certified by the Finančná správa for Slovakia? Does it handle the Latvian CTC reporting flow?
- Pre-register your Latvian and Estonian subsidiaries: even where B2B is not yet mandatory, registering as a Peppol sender costs little and enables you to test flows with major buyers that already require structured invoicing contractually.
- Check your ERP localisations: local VAT number prefixes, date formats, Lithuanian-language legal mentions for B2G invoicing.
- Plan compliant archiving: generic storage solutions (SharePoint, Google Drive) are not sufficient. You need a certified digital vault or a dedicated archiving feature in your ERP.
To explore the broader regulatory context in this region, read our e-invoicing compliance map for Central and Eastern Europe (Poland, Hungary, Romania) and our guide to the ViDA roadmap and its ERP implications. For the Slovak ERP ecosystem specifically, our 2026 Slovak ERP market guide covers local vendors (Pohoda, Money S5, OMEGA) and their eFaktúra readiness.
