myDATA Greek E-Invoicing 2026: AADE Compliance, Mandatory Submission & E-Commerce Integration

1. myDATA Platform Overview — AADE's Real-Time Tax Backbone

Few European countries have moved as decisively into real-time e-invoicing as Greece. myDATA is now the spine of every transaction recorded by every business — from a tiny taverna in Naxos to a listed retailer in Athens. The diagram below summarises the five layers the platform stitches together; keep it in mind as you read each section.

2. Mandatory for All B2B and B2C Since 2021

The Phased Rollout

The launch of myDATA was the largest regulatory project AADE has executed since its inception. The platform was first announced in 2019, opened for voluntary testing in October 2020, and became mandatory in stages through 2021 and 2022. By the end of 2022 every Greek entity — large enterprises, mid-market companies, SMEs, freelancers and even single-employee taxis — had been pulled into the system. There is, as of 2026, no Greek-resident business that operates outside myDATA.

The legal foundation is decision A.1138/2020 of the AADE Governor (and parallel decision A.1054/2021), which prescribes the technical specifications, the document type taxonomy, the transmission deadlines, and the penalties for non-submission. Subsequent decisions A.1156/2023 and A.1170/2024 tightened the deadlines and broadened the scope to include intra-Community transactions and certain accounting entries.

What Counts as a Mandatory Submission

• Every issued invoice — B2B (type 1.1), B2C retail receipts (type 11.x), B2G to public sector entities, simplified invoices, credit notes, debit notes
• Every income classification — revenue split by chart-of-accounts category, FPA rate and exemption code
• Every expense classification — purchase invoices with line-item classifications
• Payroll entries — salaries, withholdings and employer contributions (from 2023)
• Accounting adjustments — depreciations, accruals, year-end entries (from 2024)

The combination yields, for each Greek company, a real-time electronic book of incomes and expenses mirrored at AADE. Periodic FPA returns (form F2) and corporate income tax filings (form E3 / E5) are increasingly pre-populated by AADE from this live stream — manual filing is fading.

B2C E-Commerce Specifics

For e-commerce sellers, the typical document is the type 11.1 retail receipt (sale to private consumer) or, where the customer requests an invoice and provides an AFM (tax ID), type 1.1. Both flow through the same myDATA pipeline. Marketplaces such as Skroutz and platforms like Shopify must be wired to a certified myDATA channel so that each completed checkout produces a real-time XML submission to AADE within seconds.

3. XML Format — Digital Signature and QR Code

The myDATA XML Schema

myDATA documents are transmitted as structured XML conforming to the AADE-published schema (xsd files versioned per decision update — current production version v1.0.9 as of mid-2026). The schema is rich: each document carries header metadata (issuer AFM, counterparty AFM, document type code, currency, issue datetime), one or more line-item rows (description, quantity, unit price, net value, FPA category, FPA amount, withholding tax, other taxes/charges), and a summary block (totals, classifications by income/expense category).

A condensed example of the document header looks like this in practice (schema simplified):

<InvoiceHeader>
  <series>ZUNA</series>
  <aa>58271</aa>
  <issueDate>2026-06-10</issueDate>
  <invoiceType>1.1</invoiceType>
  <currency>EUR</currency>
</InvoiceHeader>
<invoiceSummary>
  <totalNetValue>100.00</totalNetValue>
  <totalVatAmount>24.00</totalVatAmount>
  <totalGrossValue>124.00</totalGrossValue>
</invoiceSummary>

Digital Signature

Each document must be digitally signed before transmission. There are two accepted mechanisms:

• Provider signature — when the document flows through a certified e-invoicing provider (the recommended path), the provider signs with its own AADE-registered certificate.
• EAFDSS signature — the legacy hardware-device signature, still accepted for businesses on the transition track.

The signature provides the legal non-repudiation that the document existed at the timestamp claimed and was transmitted by the registered party. Without a valid signature, AADE rejects the submission and no MARK is issued.

The QR Code Requirement

Every legally compliant Greek invoice or retail receipt must display a QR code encoding the issuer AFM, the document series and number, the totals, the FPA breakdown and the MARK identifier returned by AADE. The QR code is what a tax inspector physically scans to verify, at the point of audit, that the document on a customer's hands is the same document AADE accepted in real time.

The MARK Identifier

After AADE accepts the submission, the platform returns a MARK (Mnimoniako Arithmo Kataxorisis — Unique Registration Number). This 15-digit identifier is the official AADE receipt that the document has been recorded. It must be stored alongside the order in the seller's system, printed on the customer copy and surfaced in the QR code. Without a MARK, the document is non-compliant and the expense it represents cannot be deducted by the buyer.

4. Real-Time Submission to AADE

The Three Transmission Methods

Greek law recognises three approved transmission channels into myDATA, each with its own deadlines and audit footprint:

1. Certified e-invoicing provider — a private company licensed by AADE to transmit on behalf of taxpayers. Submission is real-time (within seconds of issuance). This is the recommended path for any seller with material volume.
2. ERP / accounting software with direct API access — businesses with their own AADE OAuth credentials submit directly. Deadlines remain real-time for sales documents.
3. Manual entry on my.aade.gr — feasible only for the smallest volumes; deadline is the end of the following day. Penalty exposure is highest here because every late entry triggers an A.1138 fine.

The Sub-Second Round Trip

A typical real-time transmission cycle looks like this:

• T+0ms — checkout completes on the e-commerce storefront
• T+50ms — Zunapro (or any certified provider) builds the structured XML, signs it and POSTs to the AADE REST endpoint
• T+400-800ms — AADE validates the schema, checks the counterparty AFM (via the VIES / Greek tax registry), records the document and returns the MARK
• T+1s — the MARK is persisted against the order, printed on the customer copy and encoded in the QR code

Under normal load AADE round-trips are well under a second. During peak periods (last day of FPA filing periods, end-of-year) latencies can rise to several seconds, but the platform has improved markedly since the 2021 launch — full-platform outages are now rare and measured in minutes per quarter, not per month.

What Happens When AADE Is Down

Resilience is built into the protocol. When AADE is unreachable, certified providers queue documents locally and retry. Decision A.1138 allows up to 24 hours grace for documents that could not be transmitted in real time due to verifiable AADE outage — provided the issuer captures and submits the AADE outage notice as evidence. Zunapro automates this: all retries are logged, the AADE status page is monitored, and any document delayed by an outage is flagged in the compliance dashboard for traceability.

5. Certified ERP Providers — Epsilon, Soft1, Singular and the Wider Ecosystem

The Certification Regime

AADE maintains a public register of certified e-invoicing providers — companies authorised to transmit on behalf of taxpayers. To earn certification, a provider must pass a multi-month technical audit covering schema fidelity, signature implementation, retention, security and disaster recovery. As of 2026 there are roughly 30 certified providers serving the Greek market. The five most relevant for e-commerce sellers are:

Epsilon Net — The Market Leader

Epsilon Net is Greece's largest accounting and tax-technology vendor, listed on the Athens Stock Exchange (ATHEX:EPSIL). Founded in 1999, it serves over 90,000 Greek SMEs through its ERP families: Pylon (mid-market), Hyper (full ERP), and Smart (SME accounting). All three are certified myDATA channels. Epsilon's market share is driven by tight integration with the Greek accountant ecosystem — most certified accountants prepare client books in Pylon or Hyper and trust the AADE submission pipeline implicitly.

SoftOne — Soft1 Cloud and Soft1 ERP

SoftOne, founded in 2002, is the second-largest player by share and the strongest mid-market choice. Soft1 Cloud is its SaaS edition for SMEs and e-commerce operators; Soft1 ERP serves mid-to-upper-mid-market businesses across Greece, Cyprus, Romania and Bulgaria. SoftOne is a particularly common back-office choice for retail chains and hospitality groups, both of which generate high volumes of type 11.x retail receipts that must flow through myDATA in real time.

Singular Logic — Galaxy and Enterprise

Singular Logic traces its roots to 1998 and serves banking-grade and large-enterprise clients. Its flagship products Galaxy (full ERP) and Enterprise (financials + supply chain) are used in finance, utilities, telco and the public sector. For very large e-commerce groups (multi-warehouse, multi-currency, complex inter-company), Singular's depth is hard to beat — but the cost of ownership is correspondingly higher than the SME tier.

Entersoft, Data Communication and Megasoft

• Entersoft (ATHEX:ENTER) — Entersoft Business Suite, strong in retail, hospitality and B2B verticals
• Data Communication — Premium ERP and Academia accounting suite, large foothold in mid-market
• Megasoft — Eurofasma and IES ERP, popular with small accountants and freelancers
• Computer Logic — Logic ERP and accounting, niche but well-loved by sole-trader accountants

6. FPA (VAT) Rates 2026 — 24%, 13% and 6%

Standard, Reduced and Super-Reduced Rates

Greek FPA (Foros Prostithemenis Aksias) — VAT in English — operates three mainland rates plus a reduced island regime. The 2026 rate card is unchanged from 2024-2025:

The Eastern Aegean Islands 30% Reduction

The Greek islands of the eastern Aegean — Chios, Lesvos, Samos, Leros, Kos — keep a long-standing 30% reduction on each FPA rate, designed to offset their geographic isolation. Effective rates are therefore 17% / 9% / 4%. The reduction is extended periodically by ministerial decision; the current extension runs through end-2026 and is widely expected to be renewed. For e-commerce, this means a delivery to a Chios postcode legitimately attracts 17% FPA rather than 24% on a standard-rate SKU — provided the seller correctly classifies the delivery point and AADE accepts the classification.

FPA Exemptions and Zero-Rated Categories

• Intra-Community supplies — B2B sales to other EU VAT-registered businesses are zero-rated; the recipient self-accounts via reverse charge
• Exports outside the EU — fully zero-rated, conditional on proof of export
• Healthcare, education, financial services — exempt without right of deduction
• Small-business regime — turnover under €10,000 may opt for the small-business franchise (no FPA charged, no FPA deducted)

FPA in the myDATA XML

Each invoice line in the myDATA XML carries a vatCategory field with values 1 through 8 — 1 for 24%, 2 for 13%, 3 for 6%, 4-6 for the island-reduced equivalents, 7 for zero-rated and 8 for exempt. Misclassification is a common audit issue; Zunapro maps storefront tax classes to the correct vatCategory automatically and flags discrepancies for review.

7. Penalties for Non-Compliance

The Fine Schedule

Non-compliance is enforced under the Code of Tax Procedure (KFD — Law 4987/2022), supplemented by decision A.1138/2020 and its amendments. The fine ladder is steep:

Violation	Fine	Notes
Late submission (per document)	€100	SMEs; €500 for medium-large entities
Missing submission (per document)	€250 – €500	Depends on entity category
Repeat offence (same year)	×2 multiplier	Doubled fines on second occurrence
Systematic non-submission	Up to €30,000	Cumulative annual cap; tied to turnover
Expense without MARK	100% disallowance	Cannot deduct from corporate income tax
Tax evasion (Article 66 KFD)	Criminal liability	Above €100K evaded — escalates to courts

The Deduction Disallowance — The Real Penalty

The fines are unpleasant, but the real economic penalty introduced from 2024 is the disallowance of expenses without a MARK. Concretely: if your supplier issued you an invoice for €1,000 + €240 FPA but failed to transmit it to myDATA, AADE will not accept that €1,000 as a deductible expense in your income tax return. At a 22% Greek corporate tax rate, you've effectively lost €220 of tax shield — plus the €240 FPA you cannot reclaim. The total economic exposure is more than half the invoice value, even before any administrative fines.

This is why purchase teams in Greek e-commerce groups now systematically verify that every supplier invoice carries a MARK before paying it. The MARK is the proof that the document is "alive" in AADE — and therefore deductible.

Audit Triggers

• Mismatch between e-books and FPA return — divergence above 1% triggers automated review
• Pattern of late submissions — flagged by AADE's behavioural risk engine
• Counterparty discrepancy — your sale to ABC SA does not appear in ABC SA's expense feed
• Cash-flow vs revenue mismatch — bank inflows materially exceed declared revenue
• Anonymous tip-offs — AADE operates a structured whistleblower channel

8. Cross-Border Transactions and EU VAT OSS

Intra-EU B2B Supplies

A Greek seller shipping to a German VAT-registered business issues a zero-rated FPA invoice quoting both EU VAT numbers (the Greek EL... AFM and the German DE... VAT). The transaction is submitted to myDATA as type 1.5 (intra-Community supply) with vatCategory=7 (zero-rated). In parallel, the seller files the supply in the periodic VIES recapitulative statement (form F4). The German buyer self-accounts the VAT under the reverse-charge mechanism in their domestic return.

Intra-EU B2C Distance Sales — The OSS Regime

For B2C distance sales above the EU-wide €10,000 threshold, the seller must charge the destination-country VAT rate — 21% for shipping to Spain, 21% to the Netherlands, 19% to Germany, and so on. Rather than registering for VAT in every destination country, EU sellers use the OSS (One Stop Shop) regime: register once with the Greek tax authority via the AADE OSS portal, file a single quarterly OSS return, and AADE redistributes the VAT to the destination countries.

The myDATA submission for an OSS sale is type 1.1 with the foreign VAT amount captured in the line-item fields. The Greek-rate FPA is zero (the sale is outside Greek VAT scope), but the OSS-relevant amounts are tagged for the quarterly OSS reconciliation. Zunapro automates the entire flow: per-destination VAT lookup, OSS-tagged myDATA submission, quarterly OSS report generation.

Non-EU Exports

Exports outside the EU are zero-rated under Greek VAT law, conditional on proof of export (customs export declaration). The myDATA document is type 1.1 (or 1.6 for triangular trades) with vatCategory=7 and the export-proof reference stored in the document metadata. Withholding any export proof for more than 90 days triggers retroactive FPA charging.

Import One Stop Shop (IOSS)

For consignments under €150 imported into the EU from outside (think a Chinese SME drop-shipping to Greek consumers), the IOSS regime allows the seller to pre-collect Greek FPA at checkout and pass it to AADE via a single monthly IOSS return. Marketplaces operating as "deemed suppliers" (Amazon, Skroutz Marketplace for some flows) absorb the IOSS obligation on behalf of third-party sellers — but the underlying seller still benefits from myDATA-clean records to reconcile what the marketplace remitted.

9. Integration With Amazon FBA Greece

The Greek Amazon Reality

There is no dedicated amazon.gr storefront as of 2026, and Amazon does not maintain physical fulfillment centres on Greek territory. Greek customers shopping at Amazon are served from amazon.de, amazon.it (MXP fulfillment), amazon.fr or — increasingly — from the Bulgarian-bordered FBA expansions feeding Southeast Europe. That said, Amazon Marketplace orders to Greek customers count as Greek-customer sales for the seller's tax purposes if the seller is established in Greece, and any Greek-established seller using FBA elsewhere in the EU has full myDATA obligations on every sale.

The myDATA Workflow for Greek Amazon Sellers

1. Amazon SP-API webhook — order confirmation triggers Zunapro
2. Build myDATA XML — type 11.2 (retail with shipping address) or 1.1 (B2B if AFM provided), with FPA at destination rate
3. Sign and submit — Zunapro signs and POSTs to AADE within seconds
4. Receive MARK — stored against the Amazon order ID
5. Surface invoice — Amazon's standard invoice download is populated with the MARK and QR code
6. Reconcile — at month-end, Zunapro reconciles the Amazon disbursement against the myDATA-submitted documents and flags any gaps

Pan-EU FBA from Greek Sellers

Greek sellers participating in Amazon's Pan-EU FBA programme send stock to fulfillment centres in Germany, France, Italy, Spain, Czechia, Poland and beyond. Each EU country in which inventory is stored creates a local VAT registration obligation (or OSS for B2C-only flows). myDATA captures the Greek leg — the issuance of the invoice to the EU customer — while local VAT obligations are handled via Amazon's VAT Services or a third-party EU VAT compliance partner. Zunapro bridges the two: myDATA for the Greek side, OSS + country-specific reporting for the EU side, single dashboard for the operator.

Other Greek Marketplaces

• Skroutz Marketplace — Greece's #1 price comparator turned marketplace; full myDATA integration via Zunapro
• Public.gr — books, electronics and toys; myDATA-native
• e-shop.gr — technology and PC components; myDATA via supplier ERP
• BestPrice — comparator with paid placement model

10. The Future of E-Invoicing in Greece

EU VAT in the Digital Age (ViDA)

The European Union's VAT in the Digital Age (ViDA) package, adopted in 2024-2025, sets a continent-wide trajectory toward harmonised real-time e-invoicing for cross-border B2B by 2030. Greece is unusually well-positioned: myDATA already implements most of what ViDA requires domestically, and AADE has committed to extending the platform to cover cross-border B2B digital reporting in step with the ViDA schedule. Expect a phased rollout: schema alignment in 2027, cross-border digital reporting from 2028, and full ViDA compliance by 2030.

Pre-Filled VAT Returns

AADE has piloted pre-filled FPA returns derived from the myDATA live stream since 2023. By 2026 small-business returns can be auto-generated with only a confirmation click; mid-market returns are still partly manual due to depreciation and inter-company adjustments, but the gap is closing. By 2028 the periodic F2 return is expected to be fully pre-filled for the majority of taxpayers — turning the FPA return from a monthly filing chore into a quarterly review-and-sign exercise.

Pre-Filled Corporate Income Tax

The longer-term goal is to extend the same pre-filling logic to corporate income tax forms (E3 / E5 / F01.013). AADE published a roadmap in 2025 targeting 2028 for the first pre-filled E3 / E5, drawing on myDATA's income and expense classifications. The implication is that the chart of accounts a Greek e-commerce operator uses today — every classification on every myDATA line item — directly shapes tomorrow's pre-filled tax return. Getting classification right is no longer a "the accountant fixes it at year-end" issue.

Tax Incentives for Early Adopters

• 50% extra depreciation on technology investments in certified e-invoicing tools — extended through 2026
• 100% deduction of first-year e-invoicing provider fees
• 2-year shortening of the tax-audit statute of limitations for businesses fully compliant on certified channels
• Faster FPA refunds for exporters whose income flows are entirely myDATA-tracked

Integration With AADE's AI Audit Engine

AADE has invested heavily in machine-learning risk scoring against the myDATA stream. By 2026 audits are increasingly triggered algorithmically — pattern anomalies in classification, sudden margin changes, counterparty concentration, even time-of-day issuance patterns. The takeaway for sellers: clean, classifier-correct myDATA submissions are not just compliance hygiene; they are the input that determines whether AADE's risk engine flags your business or your competitor's. Zunapro's classifier maps every storefront SKU to the correct income classification and FPA category, eliminating one of the most common audit triggers.

Greek myDATA FAQ 2026