Greece's E-Invoicing Phase B: Who Needs to File a Declaration Before October 12 — And Who Doesn't

With Greece's mandatory B2B e-invoicing deadline now just days away, the Greek Tax Authority (AADE) has published long-awaited clarifications on one of the most frequently asked questions: who actually needs to file the Declaration of Electronic Document Issuance when using the free government applications timologio and myDATAapp — and who does not.

The October 1 Trigger — What's Changing

From October 1, 2026, businesses with annual gross revenues up to EUR 1 million (based on tax year 2023) enter the mandatory electronic invoicing regime under Phase B of Greece's e-invoicing rollout. The legislation creates a three-month transition window — October through December 2026 — during which qualifying businesses can still issue invoices through legacy methods in parallel, provided they file the relevant declaration.

Key Developments: Who Needs to File and Who Does Not

The AADE guidance draws a simple but operationally critical distinction:

• Declaration REQUIRED: Businesses with revenues up to EUR 1M that wish to use the parallel transition window (October 1 – December 31, 2026) and continue issuing invoices through legacy methods alongside the new digital tools. Filing deadline: October 12, 2026.

• Declaration NOT REQUIRED: Businesses that switch exclusively to timologio or myDATAapp from October 1 onward. If you go fully digital from day one, no filing is needed.

Retail Transactions: No Change

AADE explicitly confirms that the e-invoicing mandate does not alter obligations or document issuance methods for retail (B2C) transactions. Businesses with POS terminals and retail receipt systems are not affected by these changes — a clarification that removes a major source of uncertainty for mixed B2B/B2C operators.

How to File (When Required)

The declaration is submitted through the myAADE digital portal at: Applications > Tax Services > myDATA > Declaration of electronic document issuance via Provider, Self-Provider, or timologio. For businesses using a licensed e-invoicing Service Provider (under Decision A.1112/2025), separate registration obligations remain unchanged and are not covered by this guidance.

Why It Matters for Accountants and SMEs

For accountants managing a client portfolio, this guidance simplifies the decision tree considerably. The question for each client is now binary: do they want the 90-day parallel transition, or are they ready to go fully digital on October 1? Each path has different compliance steps and a different risk profile. Businesses that miss the October 12 declaration deadline while still issuing paper invoices face direct exposure to AADE penalties — which are not negligible.

Key Takeaways

• Mandatory e-invoicing via timologio/myDATAapp starts October 1, 2026 for businesses with revenues up to EUR 1M

• Filing the declaration is required ONLY if you want the parallel transition period (until December 31)

• Declaration filing deadline: October 12, 2026

• Exclusive use of timologio from October 1: no declaration needed

• Retail (B2C) transactions: completely unaffected by these changes

Closing Insight

The October 1 deadline is no longer a distant horizon — it is an operational reality. For businesses and their advisors, the priority now is execution: choose your compliance path, file if necessary, and ensure your invoicing infrastructure is ready. Hesitation at this stage does not pause the clock. It only shortens the runway to either a clean transition or an avoidable penalty.

Source: taxheaven.gr | Read the full article here: https://www.taxheaven.gr/news/74689/