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Fiscalization in Greece — the three regimes, and how they fit together

Greek fiscalization rests on three distinct but converging regimes: myDATA (real-time reporting of all transactions, in force since 2021), the POS ↔ cash-register / ΦΗΜ interconnection (retail card flows, already in force), and mandatory B2B e-invoicing under Law 5222/2025 (phasing in through 2026–2027). They are separate obligations with separate timelines — and it matters which is which.

Why this article exists

these three are routinely confused, including in the press. They overlap in purpose — full real-time visibility of every euro — but they are distinct legal regimes with distinct deadlines. Mixing them up (for example, treating the 2026 e-invoicing dates as POS-interconnection deadlines) leads to wrong compliance planning. Here is the clean separation.

1. myDATA — real-time reporting (in force since 1 July 2021). AADE’s digital platform to which businesses transmit invoice and accounting data in near real-time. Every document gets a unique MARK id and QR code, and the data feeds pre-filled VAT returns. It applies to effectively all businesses that keep books, including sole traders. See myDATA explained.

2. POS ↔ cash-register / ΦΗΜ interconnection — retail card flows (already in force). Businesses must interconnect their card terminals (EFT/POS) with a certified fiscal device (ΦΗΜ) or certified e-invoicing software, so card payments report to AADE in real time. This is an existing, operational obligation — not a future deadline. Hospitality (hotels) is a notable ΦΗΜ-exempt vertical. See POS & cash-register interconnection.

3. Mandatory B2B e-invoicing — phasing in 2026–2027 (Law 5222/2025). Structured electronic invoicing between businesses, becoming mandatory in phases: large businesses (over €1m FY2023 revenue) from 2 March 2026 with penalties from 3 May 2026; all other resident taxpayers from 1 October 2026; full item-level classification from 1 January 2027. This is the new, time-sensitive piece. See B2B e-invoicing.

The compliance stack for a 2026 retailer, neutrally

a certified fiscal device (ΦΗΜ) or certified software, an interconnected POS, and myDATA reporting — converging with mandatory B2B e-invoicing as it phases in. Separately, since 1 December 2025, businesses must also accept IRIS instant payments. The direction of travel is full, real-time visibility of every retail and B2B transaction, with AADE cross-checking across POS, IRIS, cash registers and myDATA.

How to stay compliant

treat the three regimes as separate checklists with separate dates, and confirm each against AADE — this area is actively shifting and the deadlines have already been adjusted once. The detail articles below give the dated specifics for each.

Related

myDATA · POS & cash-register interconnection · B2B e-invoicing · IRIS is mandatory for businesses

This is general information, not tax or compliance advice. The fiscalization regime is actively changing — confirm every date and obligation against AADE (aade.gr) and your accountant or software provider. WTP Finance is informational only.

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