Greece B2B E-Invoicing 2026: Who Must Use a Certified Provider from 2 November 2026

In short: Greek B2B e-invoicing is mandatory in two phases. Businesses with 2023 gross revenue above €1 million have been in scope since 2 March 2026. All other businesses must issue e-invoices from 2 November 2026, with a transition to 31 January 2027. From 1 February 2027, invoices can no longer be sent to myDATA from ERP software.

This guide explains who must issue e-invoices in Greece, which channels are allowed, the key deadlines and what to do now. It reflects the position as of October 2026, including AADE's announcement of 30 September 2026.

What is myDATA and how does e-invoicing fit in?

myDATA is the Greek tax authority's (AADE) electronic books platform. Mandatory e-invoicing changes how invoices reach it: they must now be issued through approved channels, not just reported afterwards.

AADE describes myDATA ("my Digital Accounting and Tax Application") as the platform through which businesses keep electronic books. Businesses send invoice and accounting data to AADE in bulk from their systems or through a simple form on the AADE website.

Until the e-invoicing mandate, many businesses issued invoices in their own ERP or accounting software and then transmitted the data to myDATA. Under Decision A.1128/2025, invoices in scope must be issued "exclusively electronically", either through a certified e-invoicing provider or through AADE's own applications. AADE's FAQ states that ERP or accounting software on its own does not constitute an acceptable method of issuing invoices.

For a wider view of Greek VAT rules, see our Greece VAT manual and guide to understanding VAT in Greece.

When is e-invoicing mandatory in Greece?

E-invoicing became mandatory on 2 March 2026 for larger businesses and starts on 2 November 2026 for everyone else. Each phase has a transition period during which other issuing methods may still be used in parallel.

• Phase 1 (first period): businesses with gross revenue above €1,000,000 in their 2023 income tax return; mandatory from 2 March 2026; transition period from 2 March to 3 May 2026.
• Phase 2 (second period): all other businesses in scope, including those with 2023 gross revenue up to €1,000,000; mandatory from 2 November 2026; transition period from 2 November 2026 to 31 January 2027.
• End of the ERP route: from 1 February 2027, phase 2 businesses can issue in-scope invoices and transmit them to myDATA only through a certified provider or AADE's timologio and myDATAapp. Transmission via ERP will no longer be possible.

The phase 1 dates were confirmed in an AADE press release of 17 February 2026. The phase 2 dates, including the transition to 31 January 2027, were confirmed by AADE on 30 September 2026. Where the revenue year does not end on 31 December 2023, the return for the fiscal year starting in 2023 applies.

According to AADE, about 34,000 of 38,000 phase 1 businesses had already activated e-invoicing by February 2026. By the end of September 2026, about 655,000 phase 2 businesses (nearly 70%) already used a provider or AADE apps for wholesale invoicing.

What happens during the transition period?

During the transition, businesses may keep using their existing commercial, accounting or ERP software in parallel with the approved channels. This relief depends on filing the start declaration on time.

• Phase 1: from 2 March to 3 May 2026, parallel use of existing software or AADE's special entry form was allowed, provided e-invoicing started within that window.
• Phase 2: from 2 November 2026 to 31 January 2027, parallel use of existing software and AADE's special entry form is allowed.
• Condition: a "Declaration of Start of Electronic Issuance of Documents" (via a provider) or a declaration of use of the timologio application must be filed on time.

AADE's 30 September 2026 announcement adds that phase 2 businesses using a provider must file the start declaration with effect from 2 November 2026. Businesses that will use only timologio or myDATAapp from 2 November 2026, without the transition, do not need to file it.

Who must issue e-invoices in Greece?

The obligation applies to entities subject to the Greek Accounting Standards (Law 4308/2014). It covers sales of goods and services to Greek businesses, to businesses outside the EU and to the public sector.

Decision A.1128/2025 lists three types of transaction that must be invoiced electronically:

• Domestic B2B: invoices to another entity in Greece that is subject to the Greek Accounting Standards.
• B2B to non-EU countries: invoices to foreign businesses established outside the European Union.
• B2G: invoices relating to the performance of public contracts and to general government expenditure.

Invoices to businesses in other EU Member States and invoices to consumers are not listed in the decision's mandatory scope.

From 2 March 2026, recipients of domestic B2B and B2G invoices must accept e-invoices. Recipients therefore also need a way to receive and process them.

Foreign businesses that are only VAT-registered in Greece should check their position carefully. AADE's FAQ does not address non-established businesses explicitly. Confirm your status with AADE or a Greek adviser before 2 November 2026.

Certified provider or AADE's free apps: which channel should you use?

Businesses can issue e-invoices through a certified e-invoicing provider, through AADE's free timologio web application, or through the myDATAapp mobile app. They can combine these channels.

• Certified e-invoicing providers: private service providers whose software is assessed and licensed by a committee at AADE. They authenticate invoices, transmit them to myDATA and must retain invoice data for as long as the business must keep it.
• timologio: AADE's free desktop application for issuing and transmitting tax documents. It requires no contract with a provider and can also be used for public-contract invoices.
• myDATAapp: AADE's free mobile app. It now includes document scanning and receipt features.

AADE confirms that a business may use more than one provider and may run timologio or myDATAapp in parallel. Using a provider does not release the business from its own duty to keep accounting records.

The free apps suit businesses that issue few invoices. Businesses with high volumes or ERP-driven billing usually need a provider that connects to their existing systems. When choosing, check provider licensing, ERP integration, handling of rejected or corrected invoices, archiving and multi-country coverage.

Taxually's e-invoicing API lists Greece myDATA among its direct tax authority connections.

What format must Greek e-invoices use?

Decision A.1128/2025 does not prescribe a file format itself. The technical format depends on the channel: providers and AADE's apps generate invoices that meet AADE's myDATA specifications.

For B2G invoices, Greece transposed the EU directive on electronic invoicing in public procurement through Law 4601/2019. According to the European Commission, Greek B2G e-invoices follow the European standard EN 16931 and are exchanged through certified providers using Peppol access points. Read more in our guide to what Peppol is.

If you build your own integration, ask your provider which data model and myDATA API version it supports. AADE publishes the myDATA API documentation and XSD schemas on its website.

What are the penalties for not issuing e-invoices?

An invoice issued outside the approved channels is treated as not issued. The penalties for non-issuance of invoices in the Greek Tax Procedure Code then apply.

• Treatment: AADE Circular E.2004/2026 states that invoices issued by hand or through ERP or other software outside a provider or AADE's apps are treated as non-issuance.
• Transactions subject to VAT: a fine of 50% of the VAT that would have arisen from the invoice, or of the difference, under Article 57(5) and (6) of Law 5104/2024.
• Transactions not subject to VAT: €500 per tax audit for businesses keeping simplified books, or €1,000 per tax audit for businesses keeping double-entry books.
• Exception: manual issuance is allowed only in exceptional cases such as loss of connectivity, with later transmission.

Businesses that file their declaration early may also qualify for tax incentives. Under Article 71I of Law 4172/2013, certain e-invoicing equipment, software and first-year running costs are increased by 100% for deduction purposes, subject to conditions.

What should businesses do before 2 November 2026?

Phase 2 businesses should choose a channel, file the start declaration and test invoicing well before 2 November 2026. Plan to stop all ERP-only invoicing by 1 February 2027.

1. Confirm your phase: check your 2023 gross revenue and whether you are subject to the Greek Accounting Standards.
2. Map your invoice flows: identify domestic B2B, non-EU B2B and public-sector invoices, which are in mandatory scope.
3. Choose a channel: select a licensed provider, timologio, myDATAapp or a combination.
4. File the declaration: make sure the provider files the start declaration with effect from 2 November 2026, and accept it in time.
5. Update your systems: connect your ERP to the provider and test issuance, corrections, credit notes and receipt of supplier e-invoices.
6. Prepare to receive: make sure your team can accept and process incoming e-invoices from Greek suppliers.
7. Plan for 1 February 2027: stop transmitting in-scope invoices to myDATA directly from ERP software.

Greece is one of several countries moving to mandatory e-invoicing ahead of the EU's ViDA reforms. See our guide to electronic invoicing in the EU, our article on VAT data automation for CTC and e-invoicing and our overview of what ViDA means for businesses.

Sources

• AADE press release, 30 September 2026: phase 2 start dates and transition
• AADE press release, 17 February 2026: phase 1 dates, declarations and penalties
• AADE FAQ: mandatory electronic invoicing and digital movement documents
• Decision A.1128/2025 (Government Gazette B' 4937/16.09.2025), text
• AADE Circular E.2004/2026 on e-invoicing penalties, text
• AADE: myDATA electronic books
• European Commission: eInvoicing in Greece