Greece E-Invoicing 2026: myDATA B2B Mandate Explained

Greece e-invoicing is now mandatory for domestic B2B sales. Large businesses (gross revenue above 1 million euros in 2023) had to start issuing e-invoices through an approved channel on 2 March 2026. Every other in-scope business starts on 2 November 2026, with a transition period until 31 January 2027. Invoices must go through a licensed provider or AADE's free apps and be reported to myDATA.

That is the short answer. The details matter, because the dates have moved several times, the scope is narrower than many people assume, and the penalty for getting it wrong is tied to the VAT on each invoice. This guide covers the timeline, who is in scope, the three ways to issue a compliant invoice, the declaration you may need to file, and a practical checklist. It is written for small business owners and freelancers in Greece, and for anyone abroad who invoices Greek clients.

What Greece e-invoicing means in practice

Greece has had digital tax reporting for several years through myDATA, the platform run by AADE (the Independent Authority for Public Revenue). Businesses already send summary invoice data to myDATA, and each document gets a unique registration number called a MARK. What changes with the B2B mandate is how the invoice itself is created and transmitted.

Under the mandate, covered invoices must be issued as structured electronic invoices through one of the approved channels, not typed up in a word processor and emailed as a PDF. The invoice data reaches myDATA as part of the issuing process, so the tax authority sees the transaction close to real time. This places Greece in the group of countries that combine e-invoicing with real-time reporting, a model explained in our guide to Peppol versus clearance e-invoicing models.

Public sector invoicing (B2G) went electronic earlier, under the EU public procurement rules that Greece transposed through Law 4601/2019. The 2026 mandate extends the obligation to business-to-business sales.

Greece e-invoicing timeline: phases and deadlines

The rollout was set by AADE decision A.1128/2025 and has since been amended. The original plan started large businesses in February 2026 and everyone else in October 2026. Both dates slipped. On 17 February 2026 the Ministry of Finance and AADE moved the first wave to 2 March 2026. On 30 September 2026 decision A.1197/2026 moved the second wave from 1 October to 2 November 2026.

Wave	Who	Original start	Current start	Transition period ends
Wave 1	Businesses with gross revenue above 1 million euros in their 2023 income tax return	2 February 2026	2 March 2026	3 May 2026
Wave 2	All other in-scope businesses, including those at or below 1 million euros	1 October 2026	2 November 2026	31 January 2027
Exclusive channels	Wave 2 businesses	-	1 February 2027	Only approved channels accepted

The transition period is not a delay. Reports of the second-wave decision stress that 2 November 2026 is the start date. During the transition you may keep issuing invoices with your existing software or ERP and reporting them to myDATA the old way, while you move to an approved channel. From 1 February 2027, direct ERP-to-myDATA transmission of covered invoices is reported to stop being accepted.

Dates have changed more than once, so treat this table as accurate at the time of writing and check AADE's site for any newer decision. For the wider European picture, see our overview of e-invoicing mandates coming in 2027.

Which transactions are covered

The mandate does not cover every invoice a Greek business issues. Based on decision A.1128/2025 as summarised by advisers, the scope is:

• Domestic B2B sales between businesses established in Greece.
• B2B sales to businesses established outside the EU.
• B2G transactions, including public contracts and general government expenditure.

Two big categories are reported to be outside the mandatory scope for now:

• Intra-EU B2B supplies, which will be shaped by the EU's VAT in the Digital Age (ViDA) package later in the decade.
• Retail sales to consumers, which follow separate rules for receipts and cash registers linked to myDATA.

If most of your sales go to consumers or to EU clients outside Greece, the core B2B obligation may touch only a small share of your invoices. You still need to report those other documents to myDATA under the existing rules.

Three ways to issue a compliant invoice

Greece e-invoicing gives you a choice of channel. Pick the one that matches your volume and the software you already use.

1. A licensed e-invoicing provider

Private providers are assessed and licensed by AADE. The provider issues the invoice in a structured format, sends the data to myDATA, receives the MARK and delivers the invoice to your buyer. AADE publishes the list of approved providers. Most Greek accounting and ERP packages connect to one, so your staff keep using familiar screens. Providers charge fees, usually per invoice or by subscription, so compare pricing before you sign.

2. AADE's timologio application

timologio is a free web application from AADE for issuing invoices. It suits sole traders and small businesses with a modest number of invoices each month. You enter invoices manually, and the data goes to myDATA automatically.

3. AADE's myDATAapp

myDATAapp is the mobile option, aimed at very small businesses and professionals who issue invoices on the go. Like timologio, it is free.

What about your existing ERP? You can keep it, but after the transition it must connect through an approved provider rather than send covered invoices to myDATA directly. Businesses that run several systems can use more than one provider.

The declaration of start of electronic issuance

If you choose a licensed provider, you have to file a declaration of start of electronic issuance of documents with AADE. For the second wave, reports say the declaration must carry an effective date of 2 November 2026, and electronic issuance should begin during the transition period. Filing the declaration on time is also a condition for keeping your old software running in parallel during the transition.

Businesses that use only timologio or myDATAapp from 2 November 2026, without a gradual transition, are reported not to need the declaration. AADE sent reminders earlier in 2026 to first-wave businesses that had not filed it, including some that already used a provider, so do not assume your provider files it for you. Ask them directly.

Penalties for non-compliance

The penalty regime is what makes Greece e-invoicing hard to ignore. According to advisory summaries of AADE circular E.2004/2026 and Law 5104/2024:

• An invoice issued outside the approved channels after the transition period is treated as not issued.
• For VAT transactions, the fine is reported as 50 percent of the VAT on the invoice.
• For transactions without VAT, fixed fines per audit have been reported, with lower amounts for businesses on simplified books than for those on double-entry books.
• Manual issuance is allowed only in exceptional cases, such as a loss of connectivity, with the invoice reported later.

Here is how the 50 percent rule adds up. Suppose a small design studio issues 20 invoices a month at 2,000 euros net each, all at the standard Greek VAT rate of 24 percent. Each invoice carries 480 euros of VAT. If those invoices were issued outside an approved channel after the transition, the reported fine would be 240 euros per invoice, or 4,800 euros for a single month. Even one month of non-compliance costs far more than a year of most provider subscriptions.

Penalty amounts and audit practice can change. Treat these figures as a guide and confirm them with AADE or a Greek accountant.

What should be on a Greek invoice

The approved channels handle the technical format, but the commercial content is still your job. A compliant invoice needs the usual elements found in our VAT invoice guide, plus the Greek specifics:

Element	Notes
Supplier and buyer details	Names, addresses and Greek tax numbers (AFM), or EU VAT numbers where relevant
Invoice series and number	Sequential numbering by series; see our invoice numbering guide
Date of issue and supply	Issue promptly; Greek rules set deadlines for issuing after supply
Description, quantity and price	Clear line items with net amounts
VAT rate and amount	Standard rate 24 percent, with reduced rates for some goods and services
MARK	Assigned by myDATA when the document is transmitted

For a broader comparison of what different countries require, see invoice requirements by country.

A practical checklist for small businesses

If you are in the second wave, you have very little time. Work through these steps now:

1. Confirm your wave. Check the gross revenue in your 2023 income tax return. At or below 1 million euros means the 2 November 2026 start.
2. List your invoice types. Separate domestic B2B, non-EU B2B, B2G, intra-EU and consumer sales. Only the first three fall under the mandate.
3. Choose a channel. Low volume and simple invoices may fit timologio or myDATAapp. Regular volume and accounting software usually point to a provider.
4. Ask your software vendor which provider it connects to and what changes on your screens.
5. File the declaration if you use a provider, with the correct effective date, and keep proof of filing.
6. Clean up master data. Make sure customer AFMs, addresses and product VAT codes are correct, because errors are rejected or flagged in real time.
7. Run test invoices during the transition and check that each gets a MARK.
8. Train whoever issues invoices on the new workflow and the rules for exceptional manual issuance.

If you invoice Greek clients from abroad

The mandate is aimed at businesses established in Greece and Greek permanent establishments. A freelancer or company based elsewhere that sells services to a Greek business is generally not issuing Greek e-invoices, and cross-border B2B services within the EU usually follow the reverse charge rules. Your Greek client may still ask for specific details, such as their AFM and VAT number on your invoice, so they can record the purchase correctly in myDATA. If you have a fixed establishment or VAT registration in Greece, get local advice, because the rules for non-established businesses are detailed.

Where a PDF invoice still fits

A browser-based PDF tool like our free invoice generator does not produce Greek e-invoices, does not connect to myDATA and cannot obtain a MARK. For transactions inside the mandate you need a licensed provider or AADE's apps. A PDF invoice is still useful for documents outside the mandate, such as invoices from a non-Greek business to Greek clients, quotes and pro forma invoices, and as a readable copy for your records. Our explainer on e-invoices versus PDF invoices covers the difference in detail.

Conclusion

Greece e-invoicing is live for large businesses and starts for everyone else on 2 November 2026. Confirm your wave, pick a channel, file the declaration if you need one, and test before the transition ends on 31 January 2027. This guide is general information, not tax advice. Check the latest AADE decisions and speak to a qualified Greek accountant about your own situation. For invoices outside the mandate, you can still create a clean PDF in minutes with our free invoice generator and browse more guides in our tax compliance section.