Briefing Document & Podcast – Greece E‑Invoicing, E‑Reporting, and E‑Transport: Scope, Timeline & Requirements

E-Invoicing and E-Reporting in Greece: Scope and Implementation Timeline

1. Implementation Timeline (Past, Current, Future) and Grace Periods

• 2019–2020 (Legal Framework Established): Law 4646/2019 introduced the legal basis for electronic invoicing and digital bookkeeping (the myDATA e-books system). Ministerial Decision 1017/2020 defined the e-invoice format for B2B usage. These set the stage for voluntary adoption and pilot phases. [flick.network] [ec.europa.eu]
• 2021 (Digital Reporting “myDATA” Go-Live): After pandemic-related delays, the myDATA platform (My Digital Accounting and Tax Application) became operational. Since 1 October 2021, Greek businesses have been obliged to transmit their invoice data and accounting records to the tax authority (IAPR) electronically. All companies keeping books under Greek accounting standards must comply (non-resident companies without Greek books are out of scope). This e-reporting mandate requires businesses to send summaries of all sales invoices (B2B, B2C, B2G) and certain purchase invoices to myDATA in XML format, updating the taxpayer’s electronic ledgers in real time. (During 2021–2022, the authorities allowed phased implementation and grace periods for reporting prior year data and initial alignment.) [edicomgroup.com] [snitechnology.net] [snitechnology.net], [snitechnology.net] [ey.com], [ey.com]
• 2023 (B2G E-Invoicing and Expanded Reporting): Law 4972/2022 (effective April 2023) and related decisions mandated Business-to-Government (B2G) e-invoicing in phases. Since September 2023, major public agencies started requiring e-invoices via the Peppol network. By January 1, 2024, all central government entities had to be ready to receive e-invoices, and by June 1, 2024 other public bodies joined. From January 1, 2025, all general government agencies must receive and process electronic invoices for contracts above €2,500. On the reporting side, Decision Α.1170/2023 introduced new myDATA requirements from 2024 (e.g. mandatory reporting of delivery notes, POS transactions, and a QR code on all invoices issued via software as of 1 Jan 2024). These measures enhanced real-time data capture in anticipation of broader e-invoicing. [edicomgroup.com] [ec.europa.eu] [ey.com], [ey.com]
• 2024 (Transition toward Full Mandate): As of January 1, 2024, Greece implemented pre-filled VAT returns using myDATA data (details in Section 7). Taxpayers must ensure that all invoice revenue and expense data for each period are reported before the VAT return deadline. Also, from 2024 any invoice issued through an accounting system or the AADE “Timologio” portal must include a QR code for verification. This year serves as a transition with strong incentives to adopt certified e-invoicing solutions ahead of the B2B mandate. [ey.com] [ey.com], [ey.com]
• July 25, 2025 (Legislation for B2B Mandate): The Greek Parliament passed a law (part of the “National Customs Code and Other Provisions” act, Law 5222/2025) that formally establishes mandatory B2B e-invoicing and outlines the phased implementation. Joint Decisions A.1128/2025 and A.1129/2025 (issued in Oct 2025) detail the scope, timelines, and procedures for the rollout. No immediate B2B mandate in 2025 – instead, the law allows a lead time of about 12+ months for businesses to prepare. (Early adopters in 2025 could benefit from tax incentives, see Section 5.) [vatit.com], [vatit.com] [wts.com]
• ** July 1, 2025: (Planned) Although not a mandate date, note that effective mid-2025 Greece obtained EU permission (Council Implementing Decision of 25 February 2025) to derogate from the VAT Directive and require domestic B2B e-invoicing. This cleared the way for the 2026 mandate.
• September 1, 2025 (B2G Full Enforcement): From this date, all suppliers to the general government must issue structured e-invoices for public sector transactions over €2,500, in compliance with the European standard (EN 16931). In practice, this means B2G e-invoicing is fully mandatory for relevant transactions by late 2025, completing the public procurement phase-in. [ec.europa.eu]
• February 2, 2026 (B2B Mandate Phase 1 Begins): This is the start date for mandatory e-invoicing for large enterprises. Any business with 2023 annual revenue over €1 million must issue all invoices electronically via myDATA from 02/02/2026. A transition (grace) period from Feb 2 to March 31, 2026 is provided, during which these businesses can gradually switch to e-invoicing while still using existing invoice methods in parallel. By April 1, 2026, however, these large entities are expected to be exclusively issuing e-invoices. During the grace period, companies must submit a “Declaration of Commencement of Electronic Issuance” (or opt to use the government’s Timologio app) to signal their transition. (Early adoption incentive: If these companies adopted e-invoicing by Dec 1, 2025 – two months early – they qualify for special tax benefits, see Section 5.) [kpmg.com], [edicomgroup.com]
• October 1, 2026 (B2B Mandate Phase 2 Begins): All remaining businesses (all sizes below the Phase 1 threshold) must start issuing e-invoices from 01/10/2026. A transition period from Oct 1 to Dec 31, 2026 is given for gradual compliance in this group. By January 1, 2027, e-invoicing will be fully enforced for all B2B transactions in scope. During Q4 2026, smaller businesses can still use existing invoicing methods in parallel provided they have registered their intent to comply (via an e-invoicing provider or Timologio) by the mandate start date. [kpmg.com], [wts.com] [wts.com]
• Grace Periods: In summary, grace/transitional periods are built into the B2B rollout: 2 months in early 2026 for large companies and 3 months in late 2026 for others, allowing parallel invoicing methods and ramp-up. These are not full exemptions from compliance, but rather a short window to adjust systems. There is no general “penalty-free” holiday explicitly announced beyond these periods – businesses are expected to comply by the deadlines, though enforcement in the initial weeks may be lenient as long as the formal transition declaration is made. (Notably, Greece chose a lengthy lead time; the first mandate takes effect over 18 months after the law, reflecting an implicit grace period for preparation in 2024–2025.) [wts.com], [wts.com] [wts.com]

2. Scope of Transactions Covered by the Mandate

• Domestic B2B Transactions: Business-to-Business sales within Greece are the core focus of the e-invoicing mandate. From the applicable start dates, every sale of goods or services between VAT-registered entities in Greece must be invoiced electronically via the approved system. This is often referred to as “wholesale” transactions. All sectors and industries are included (no exemptions by sector) – if both supplier and customer are subject to Greek VAT accounting, their invoices must go through myDATA. (Small B2B transactions are treated the same as large ones; there is no invoice value threshold for B2B – the mandate is comprehensive.) [ey.com], [wts.com]
• Cross-Border Transactions (Intra-EU vs. Non-EU): Greece distinguishes between EU and non-EU counterparties:
  • Intra-EU B2B: For B2B transactions with EU-based business partners, e-invoicing is allowed but not mandatory. Greek suppliers may issue a structured e-invoice via myDATA with the buyer’s prior consent, but if the EU buyer does not accept e-invoices, the supplier can revert to traditional invoicing. In other words, e-invoicing for intra-EU transactions remains voluntary (in line with EU law requiring buyer consent). Traditional invoices (with subsequent reporting to myDATA) are permitted for intra-Community sales and acquisitions until any future EU-wide mandate (such as under the upcoming “VAT in the Digital Age” reforms). [edicomgroup.com], [ey.com]
  • Extra-EU B2B (Import/Export): For transactions with businesses outside the EU (third countries), Greece is treating these similarly to domestic invoices. Exports of goods/services to non-EU customers and imports (purchases) from non-EU suppliers are within the e-invoicing mandate. Practically, this means a Greek company must issue an e-invoice for sales to a non-EU company (except retail sales), and must report purchases from non-EU entities. The law explicitly includes “wholesale transactions with entities outside the EU” in the mandatory scope. (Of course, foreign companies outside the EU are not themselves using the Greek platform; rather, the Greek seller or buyer handles the reporting. For example, if a Greek company buys services from a US firm, the Greek recipient will self-report that invoice into myDATA for record-keeping, since the US issuer isn’t on the system.) [edicomgroup.com], [ey.com] [ey.com], [wts.com] [snitechnology.net]
  • Intra-EU vs Extra-EU Summary: Domestic and non-EU B2B invoices must be electronic, while intra-EU B2B invoices can remain on paper/PDF if the foreign party opts out. All such transactions, however, must be reported to myDATA (either by the issuer or the recipient) to ensure the tax authority has the data. [edicomgroup.com], [ey.com]
• B2G (Business-to-Government) Transactions: Invoices issued in the context of public procurement or to any government entity in Greece are mandated to be electronic. Since 2023–2025, Greece has implemented the EU Directive 2014/55/EU on public e-invoicing. All suppliers contracting with the Greek public sector for contracts over €2,500 must send e-invoices that comply with the European standard (EN 16931). The Greek public sector uses a dedicated platform (National Interoperability Center – “KE.D”) and the Peppol network to receive these invoices. As of 1 September 2025, this requirement covers all general government bodies and their suppliers. In practice: [ec.europa.eu], [ec.europa.eu] [edicomgroup.com], [ec.europa.eu]
  • Public entities must be able to receive electronic invoices (via Peppol BIS 3.0 format) and private suppliers must issue them. [edicomgroup.com]
  • E-invoicing is mandatory for B2G in Greece already, ahead of the B2B rollout. For example, a company billing a Greek Ministry or municipal authority must use an e-invoice (structured XML) sent through a certified provider or the state system.
  • Exceptions: There are minor temporary exceptions for certain public contracts or specific entities during the phased roll-out (e.g. some smaller entities had later deadlines), but by 2025 virtually all B2G invoices need to be electronic. This B2G obligation is backed by national law (Law 4308/2014 as amended and JMD 52445/2023), and it encompasses all “General Government” expenditures over the threshold. Greece adopted Peppol BIS Billing 3.0 CIUS as the format for B2G invoices. [edicomgroup.com] [ec.europa.eu] [ec.europa.eu], [ec.europa.eu]
• B2C (Business-to-Consumer) Transactions: Business-to-Consumer invoices (receipts to private individuals) are not required to be electronic invoices under the current mandate. The use of e-invoices for B2C remains optional. For retail sales, Greek businesses will continue issuing paper receipts or receipts from cash registers, albeit with those transactions also reported to AADE via different channels (e.g. connected cash register systems or periodic myDATA submissions for retail totals). In summary, there is no mandatory consumer e-invoicing in Greece – a store or service provider doesn’t have to send an invoice in XML to a private customer. However, the sale still gets recorded in the myDATA system for tax purposes (e.g. through daily Z-reports or point-of-sale integration). Also, if a business chooses, it may issue a structured e-invoice to a consumer (some may do so for record-keeping, but the consumer isn’t obliged to accept it electronically). [flick.network], [flick.network] [ey.com], [ey.com]
• Taxable Person Scope – Established vs. Non-Established: The e-invoicing rules primarily apply to entities established in Greece (or those with a fixed establishment in Greece) that keep books under Greek GAAP. All VAT-registered businesses in Greece, including corporations, partnerships, self-employed professionals, and freelancers, are in scope for myDATA reporting and, when applicable, e-invoicing. No sector or entity type established in Greece is exempt from participating in the electronic reporting/invoicing regime. [flick.network], [flick.network] [flick.network]
  • Non-established businesses (foreign companies) without a Greek presence are generally out of scope of directly using myDATA. For example, a foreign company selling into Greece would not itself log into myDATA to report invoices. Instead, the Greek side of the transaction (the customer, via self-billing of purchases, or a tax representative if one is appointed) assumes the reporting duty. Foreign companies merely VAT-registered in Greece (without local establishment) are not explicitly addressed in the e-invoicing mandate, but since they are “persons not subject to Greek accounting standards,” their Greek customers must transmit those purchase invoices to myDATA. In summary, the obligation to issue e-invoices lies with Greek-resident businesses. Non-established taxpayers are indirectly covered through requirements on their Greek trading partners to report any invoices not transmitted by the issuer. [snitechnology.net]
  • Established in Greece: If a company is established or has a branch in Greece and is required to keep Greek accounting books, it must comply with both e-reporting and e-invoicing mandates. This includes subsidiaries of foreign multinationals in Greece, Greek branches of foreign companies (which are considered taxable persons in Greece), etc. [snitechnology.net]
  • Government Suppliers (Greek or foreign): For B2G, even foreign suppliers to the Greek government need to send e-invoices via Peppol. In practice they’d do so through Peppol Access Points and the invoice flows into AADE/KE.D – this is enforced as part of contract terms (foreign suppliers must use the standard). So B2G effectively ropes in even non-Greek companies when dealing with Greek authorities, by requiring compliance with the European e-invoicing standard. [edicomgroup.com]
• Transactions Not Covered / Voluntary: Transactions that are purely between private individuals or involve parties not in a business capacity aren’t relevant (no invoicing needed). Also, B2C transactions are currently outside the mandatory e-invoice scope (though still reported). Intra-EU B2B remains voluntary e-invoicing. Greece is awaiting EU’s ViDA directive for a broader intra-EU mandate in the future. Until then, such invoices are handled via the existing VAT reporting (and the Greek system can accommodate them as reported data, even if not exchanged as e-invoices). [ec.europa.eu], [ec.europa.eu]

3. Technical Format of E-Invoices and Data to be Reported

• Standardized Format (EN 16931): Greek electronic invoices must be issued in a structured electronic format (XML/UGB) that conforms to the European e-invoicing standard EN 16931. The Greek implementation uses schemas aligned with this standard, ensuring invoices contain all mandatory elements (buyer/seller details, VAT numbers, invoice date/number, line item details, tax rates, totals, etc.) in a machine-readable form. For B2G, the format is specifically Peppol BIS 3.0 CIUS (a compliant XML) as required by EU directive. For B2B, AADE’s myDATA schema applies (also XML or JSON structure based on EN 16931 core). In practice, businesses will either use an accounting/ERP software that outputs invoices in the required XML format or use a certified service provider’s platform to generate the invoice in that format. [flick.network], [flick.network] [ec.europa.eu] [flick.network]
• Unique Invoice Identifier (MARK): When an invoice is transmitted to the myDATA platform, the tax authority validates it and assigns a unique registration number (called “MARK”) as proof of successful submission. This MARK is essentially a clearance code. It must be included on the final invoice that the supplier provides to the buyer (e.g., printed on a PDF copy or visible in the e-invoice). The MARK confirms that the invoice data is lodged with AADE, functioning similarly to Italy’s SdI clearance number. Invoices without a MARK are considered not reported/cleared. [flick.network], [flick.network] [flick.network]
• Data Fields: The e-invoice must carry all information required by Greek and EU VAT law (e.g. supplier and customer names, addresses, VAT IDs, invoice number/date, description of goods/services, quantity, net amount, VAT rate, VAT amount, etc.). The myDATA schema also requires classification codes for each invoice (sales or expense type) and other supplemental info for proper bookkeeping. Key document types are coded (e.g., invoice, credit note, self-billing invoice, etc.), and each transmitted invoice includes these codes. In addition to invoice header and line data, companies must also transmit: [snitechnology.net]
  • “Classifications” – i.e., labeling each invoice line as revenue or expense category (for the ledger). [snitechnology.net]
  • Accounting adjustment entries – like payroll, depreciation, etc., which are not invoices but affect the tax results. [snitechnology.net]
  Essentially, myDATA constitutes the electronic Books: a “Detailed Transactions Book” where every invoice (sales and purchases) is recorded, and a “Summary Book” aggregating results monthly/yearly. Companies must report: [snitechnology.net]
  • All issued sales invoices (B2B, B2C, B2G) – sending a summary of each invoice’s data. [snitechnology.net]
  • Purchases/expenses – if the issuer didn’t report them (e.g. invoices from abroad or from small suppliers), the recipient must report the purchase record. [snitechnology.net]
  • Retail sales – cash register receipts are transmitted either through connected fiscal devices or summarized via myDATA (with special document types for retail/POS sales). [ey.com]
  • Other documents – credit notes, self-billed invoices, delivery notes (from 2024), payment receipts, etc., each with specified data fields to transmit. [naftemporiki.gr], [naftemporiki.gr]
• Real-Time or Near-Real-Time Transmission: Greece’s model is a clearance or continuous reporting hybrid. For e-invoices under the mandate, the expectation is that they are transmitted to AADE essentially at the time of issuance so that a MARK can be received and the invoice validated before it is considered a final legal invoice. This is similar to a clearance system: the invoice is “born digital” and cleared through myDATA in real-time. In fact, as of January 2024 a QR code is required on invoices, which likely encodes the MARK or a link to the AADE verification, underscoring that invoices should be reported immediately upon issuance. [edicomgroup.com], [edicomgroup.com] [ey.com], [ey.com]
  • For companies using certified e-invoicing providers or ERP integration, this process is automated: each invoice triggers an API call to myDATA, gets a MARK, and then can be delivered to the buyer (or made available for download). [flick.network], [flick.network]
  • The law allows a brief parallel run in transitional periods (where invoices can be issued by existing means and later uploaded), but outside those windows and going forward, invoice data must be sent promptly. If an invoice is not transmitted in time, the buyer is empowered to report it (after the fact, before filing VAT return) to ensure the tax authority is aware. This design implies that the absence of timely reporting is a violation (see Section 6 on penalties for late/non-transmission). [ey.com]
• Platform and Channels: In technical terms, businesses have two main options to send data:
  • Via a Certified Service Provider: Greece has accredited several e-invoicing service providers (Licensed Providers) that can issue invoices on behalf of businesses and transmit them to AADE. Providers like EDICOM, EpsilonNet, etc., are certified for both B2B and B2G e-invoicing. Many companies will use these providers’ platforms, which ensure the correct format/fields and handle the transmission. [kpmg.com], [ey.com] [edicomgroup.com]
  • Via AADE’s Free Portal (Timologio) or Mobile App: The tax authority offers “Timologio” (an online invoicing portal) and a myDATA mobile app, which businesses – especially small ones or freelancers – can use at no cost to create and send e-invoices. These tools directly connect to myDATA and are suitable for low volumes. Timologio essentially lets you manually input invoice details into a web form and then generates the XML and MARK. [kpmg.com]
  • ERP/API Integration: Larger businesses can integrate their own ERP or billing systems directly with the myDATA API. AADE issues each taxpayer API credentials (user ID and secret key) to allow their software to connect securely and transmit invoice data in bulk. Many businesses have updated their software or use middleware (such as SAP add-ons or SNI/Sovos solutions) to automatically send invoices to myDATA in real time. [flick.network] [snitechnology.net], [snitechnology.net]
  • Peppol for B2G: For invoices to the public sector, if using a provider, it will often route via Peppol to the government’s KE.D hub. (E.g., an invoice to a Ministry: the provider sends it first to myDATA for clearance/MARK, then forwards it through the Peppol network to the receiving entity’s system). AADE’s system is integrated with the public sector’s so that one submission can satisfy both reporting and delivery. [edicomgroup.com], [edicomgroup.com]
• MyDATA E-Reporting (for non-mandated invoices): It’s important to note that even when a transaction isn’t subject to mandatory e-invoicing (e.g. a B2C sale or an intra-EU purchase), the data still must be reported to the tax authorities via myDATA. This is the “e-reporting” function:
  • For sales to consumers (retail), businesses use certified cash registers or POS systems that send daily sales totals to AADE (e-send system) and/or summarize those in myDATA monthly. [ey.com]
  • For intra-EU B2B sales, a Greek seller who issues a paper or PDF invoice must still transmit a summary of that invoice’s data to myDATA for the period.
  • For purchases from foreign or non-compliant suppliers, the Greek buyer uses special document types to report the expense in myDATA (marked as “self-issued” or “foreign invoice”). [snitechnology.net]
  • The deadline for reporting these has been tightened: effectively, all invoices pertaining to a VAT period should be reported before the VAT return for that period is due. This ensures the pre-filled return (see Section 7) can be accurate. [ey.com], [ey.com]
• Validation and Controls: AADE’s system performs validations on the data. If an invoice submission has errors (schema errors, arithmetic mismatches), it can be rejected, requiring correction. Only once accepted and assigned a MARK is it considered reported. Authenticity and integrity of e-invoices are ensured by the system (each invoice is digitally signed by the issuer’s credentials or the provider’s, and the QR code/MARK allows verification). Buyers must accept e-invoices – as of Feb 2026, by law, Greek businesses cannot refuse an e-invoice from a supplier (it’s deemed accepted by default). The only case of rejection is if a public entity has a specific exemption or issue, but generally, the electronic format is legally equivalent to paper and must be accepted. [vatit.com] [wts.com]
• Archival of E-Invoices: Greek regulation requires that electronic invoices be stored in their original electronic form and remain accessible for auditing. Suppliers must archive all e-invoice files and the associated delivery receipts/validation logs electronically. Paper printouts are not a substitute – since authenticity relies on the digital format, invoices must be kept digitally. Key points on archiving: [flick.network] [dfkcy.com], [dfkcy.com]
  • Retention Period: The minimum retention period is 6 years from the end of the fiscal year of the invoice (this aligns with Greek tax record retention rules). In practice, many businesses keep records for 10 years. The exact period is governed by the general tax code – currently at least 5 years after the submission of the relevant annual tax return, which effectively comes out to about 6 calendar years. Thus, e-invoices must be kept for at least six years (and often longer if required for corporate law or other purposes). [dfkcy.com]
  • Format and Access: Invoices must be stored in the original format they were issued/received (e.g., XML files with their digital signature or MARK). They can be converted to other formats for convenience, but the original must be retained alongside. It is not sufficient to just print them to paper – deleting the digital copy is not allowed. The archive can be kept electronically anywhere (including on cloud servers or even in another EU country), as Greek law does not mandate local storage, provided the records can be produced on request. [dfkcy.com]
  • Accessibility: The archive should be organized such that tax auditors can retrieve specific invoices easily. Businesses typically must ensure an audit trail linking their accounting entries to the stored e-invoices. The invoices should be human-readable on screen (so either accompanied by a PDF rendering or using a viewer for XML).
  • Archiving Providers: If using a service provider, they often provide an archiving solution. The 100% additional deduction incentive also covers costs of electronic archiving for the first year (encouraging proper archival). [ey.com], [vatit.com]
  In summary, archiving requirements in Greece mean keeping the e-invoices in original electronic form for at least 6 years and ensuring they remain unchanged, legible, and available to AADE upon inspection. Compliance with authenticity and integrity over the retention period is crucial (e.g., retaining the AADE MARK and any digital signatures or hashes as proof that the invoice was not altered post-issuance). [dfkcy.com]

4. Data Transmission Deadlines and Process (E-Reporting Timelines)

• Sales Invoices: For invoices issued under the e-invoicing mandate, transmission is effectively instantaneous with issuance (a clearance model). The invoice is considered issued only after it’s sent to myDATA and a MARK is received, so by definition it’s on time if done during issuance. There’s no separate grace period measured in days; it’s a real-time requirement. [flick.network], [flick.network]
  • For sales invoices not yet mandated as e-invoices (e.g. intra-EU B2B or B2C), there were historically deadlines – initially monthly or quarterly in 2021. Currently, the rule is that all revenue for a period must be reported by the VAT return due date for that period. In fact, from 2024, the system automatically populates the VAT return, meaning if something is not reported by the time the return is due, it will show as a discrepancy. So effectively the deadline for transmitting an invoice’s data is the end of the reporting period (typically monthly or quarterly) and in practice by the 20th of the next month (the standard VAT return deadline). [ey.com]
  • Some sources indicate that late transmission after the VAT return is filed is considered non-compliance and subject to penalty (though the data can still be sent late with a fine applied – see Section 6).
• Purchase Invoices (received): If a supplier fails to report a purchase that your company received, or the supplier is foreign, the buyer must self-report that document by the VAT return deadline as well. New rules limit how long a recipient can wait: any omission or discrepancy by the supplier must be addressed by the buyer before the buyer’s VAT filing for that period. This encourages recipients to ensure all purchases are recorded in myDATA promptly. If neither party reports an invoice, it will result in a mismatch and potential penalties. [ey.com] [ey.com], [ey.com]
• Payroll, Adjustments, etc.: Non-invoice data like payroll entries, depreciation, stock adjustments needed for annual accounts have their own deadlines (often by the annual income tax return). As of the new rules, payroll and adjustment entries should be reported within the fiscal year (and absolutely before the income tax return is filed) to allow pre-filling of statements. Not reporting those on time can lead to a flat fine (per Section 6). [naftemporiki.gr]
• Real-Time vs Batch: While large companies may send each invoice in real-time, smaller ones or some may opt to batch-upload at day’s end or month’s end. Up to 2023, Greece allowed some periodic batch reporting (e.g., monthly summaries), but with the move to pre-filled VAT returns, the tolerance for delay has reduced to near-real-time. In 2023, as a transition, authorities allowed 2022 data to be transmitted by early 2024 without penalty, but going forward, the system expects continuous reporting. [ey.com]
• Delivery Notes (e-transport): A noteworthy addition: Greece is introducing electronic delivery notes reporting to track goods in transit. A pilot started in early 2024, with full implementation before end of 2024. This will likely require businesses to report dispatch documents in real time when goods are shipped. The deadline for these is envisioned as at the time of dispatch (to enable real-time transport audits). From the draft rules, failing to report a delivery note leads to specific fines (see Section 6: €100 per missing delivery note, up to €500/day). [ey.com] [naftemporiki.gr], [naftemporiki.gr]
• Summary: In practical terms, Greece’s e-reporting timeline is “as fast as possible, no later than the tax return for the period.” Invoices should ideally be reported on the day of issuance (and must be, if under clearance). At the very latest:
  • Periodic VAT payers (most businesses, monthly or quarterly) – all invoices of a given month/quarter must be in myDATA before the 20th of the following month (for monthly filers) or by the quarterly deadline.
  • Annual filings (like annual adjustments) – by the time of the annual return (e.g. by end of March for the previous year’s adjustments, depending on tax deadlines).
  Greece’s system is essentially continuous transaction control: each transaction eventually hits the platform in close temporal proximity to its occurrence. The move to zero tolerance in 2025 (0% deviation) enforces that behavior. If something is not transmitted on time, the only way to correct the VAT return is to amend it after later transmission – which is discouraged and can trigger fines. [sovos.com], [sovos.com]
• Platforms and Transmission Modes: Data are transmitted via the methods discussed (API, portal, etc.). For small taxpayers or edge cases, AADE provides a “special entry form” on myDATA for manual entry of data of an invoice if needed (for instance, if a supplier did not report it, the buyer can input the key fields via this form). Point-of-sale systems also tie into AADE’s separate “ESEND” system, but from 2024 even those must also update myDATA (with either detailed or aggregated retail data) monthly. [snitechnology.net] [ey.com]

5. Incentives for Early Adoption and Compliance Options

• Early Adoption Tax Incentives: Companies that voluntarily started exclusive e-invoicing before it became mandatory earned significant tax benefits. Under Article 212 of Law 5222/2025 and Decision A.1129/2025:
  • 100% super-deduction on expenses related to issuing e-invoices (transmission and archiving costs) for the first 12 months. [ey.com], [wts.com]
  • 100% immediate depreciation of any equipment or software purchased to implement e-invoicing. These effectively halve the cost of compliance for early movers. To qualify, large businesses had to opt in by Dec 1, 2025, and others by Aug 3, 2026. The incentives are withdrawn if the business fails to actually comply (e.g., if they declare early adoption but then issue paper invoices). [ey.com], [wts.com] [kpmg.com], [wts.com] [ey.com]
• Compliance Options: Businesses can choose between certified e-invoicing providers or AADE’s free Timologio platform to meet their obligations. This flexibility ensures even small firms can comply without needing expensive software (they can use the free government tool). [kpmg.com], [wts.com]
• No Transaction Fees: Greece does not charge per-invoice fees on the myDATA platform. The only costs are if using a private provider (subscription fees), or implementation costs for integration.
• Gradual Phases: The phased approach (large then small businesses) and transitional periods were deliberately chosen to give businesses time to adjust and learn from early adopters. [kpmg.com], [kpmg.com]
• Training & Support: AADE has published technical documentation, held webinars, and updated the myDATA specifications continuously (e.g., Decision A.1138/2020 and its amendments) to help taxpayers implement the changes.

6. Penalties for Non-Compliance

• Invalidity of Non-Reported Invoices: Perhaps the most immediate consequence: any sales invoice that is not submitted through the myDATA platform is deemed invalid for VAT purposes. This means the buyer cannot legally claim input VAT credit on an invoice that isn’t in the system, and the seller technically has not met its bookkeeping obligations. In practice, this rule pressures both parties – the seller risks its invoice being ignored for tax deduction, and the buyer will demand a compliant invoice. Thus, failing to issue an e-invoice (once mandated) effectively nullifies the invoice in the eyes of the tax authority. (The buyer would likely self-report it as an omission if the seller didn’t, which could trigger penalties for the seller.) [flick.network]
• Monetary Fines for Non-Transmission: Greek tax law (as updated by Law 4972/2023 and Law 5073/2023) sets substantial fines for not transmitting required data to myDATA:
  • If a business fails to transmit the summary of an issued invoice (sales invoice), or certain self-billing documents, the fine is 10% of the net value of that invoice, capped at €250 per day and up to €100,000 per tax year. This is a hefty penalty meant to penalize missing invoices – e.g., a €5,000 invoice not reported could incur a €500 fine, and repeated misses can accumulate up to the caps. [naftemporiki.gr], [naftemporiki.gr]
  • If a business does not transmit necessary accounting entries (like payroll, depreciation, etc.) or fails to transmit classifications for revenue which then don’t match the tax return, there is a fixed fine of €250 per year (for single-entry bookkeeping taxpayers) or €500 per year (for double-entry books) for each such violation. These cover failures that affect the reconciliation between myDATA and the income tax return. [naftemporiki.gr], [naftemporiki.gr]
  • If a seller under-reports an invoice’s value and only corrects it after the buyer flags a discrepancy, a fine of 5% of the unreported amount applies. [naftemporiki.gr], [naftemporiki.gr]
  • Failure to transmit transport documents (delivery notes) carries €100 fine per document not sent, capped at €500 per day and €20,000 per year. [naftemporiki.gr], [naftemporiki.gr]
  • Failure to transmit other auxiliary documents (like receipts of collection, order confirmations, etc.) sees a €100 fine per document (with no large cap explicitly mentioned, except that if the related sales invoice was properly issued before any audit, a receipt omission might be excused). [naftemporiki.gr]
  • Late transmission: If the data is sent but after the deadline (i.e. reported late rather than not at all), the fines are 50% of the above amounts for the cases of sales invoices, accounting entries, and delivery notes. So tardiness is penalized, though at half the rate of total failure. [naftemporiki.gr]
  • Repeat offenses: If the same offense is repeated within five years, fines can double on the second offense and quadruple on subsequent offenses, up to the maximum caps where applicable. This escalation clause means a persistent failure to report invoices over multiple years could quickly reach the annual maximums and potentially other sanctions. [naftemporiki.gr]
• Business Sanctions: In addition to financial fines:
  • The law provides that businesses who do not comply with e-invoicing cannot participate in public tenders or contracts. Non-compliance can lead to exclusion from government procurement opportunities – a significant business deterrent for those who deal with the public sector. [flick.network]
  • There are also provisions (outside e-invoice specific laws) allowing the tax authority to impose temporary closure of a business establishment for serious offenses (e.g., repeated failure to issue required receipts/invoices). With myDATA, if a firm systematically fails to transmit invoices (essentially akin to not issuing invoices), it could be seen as tax evasion, potentially leading to such measures.
  • Because unreported invoices are invalid, a buyer who cannot find their purchase in myDATA might refuse payment or demand a compliant re-issue, creating business-to-business pressure to comply.
• Penalties for Using Unapproved Methods: From 2024, there are also fines for using unauthorized software (e.g., issuing invoices from unregistered software that doesn’t link to myDATA). These ensure companies don’t try to bypass the system by using fake or offline invoicing tools. For example, issuing an invoice outside the mandated channels (licensed provider or Timologio) after one has declared to use e-invoicing can trigger withdrawal of incentives and other penalties. And using a modified cash register or software to avoid reporting is illegal, with separate fines. [ey.com]