Briefing Document & Podcast: Greece E‑Invoicing & E‑Reporting

Executive conclusion

Greece operates a layered digital VAT-control framework:

• myDATA electronic books and transaction reporting already require Greek businesses to transmit revenue, expense and accounting classifications to the Independent Authority for Public Revenue, commonly referred to as AADE or IAPR.
• Mandatory structured B2B e-invoicing is being introduced in two phases during 2026. Phase 1 applies from 2 March 2026 to entities whose 2023 gross revenue exceeded EUR 1 million. Phase 2 started on 1 October 2026 for the remaining entities, subject to a transitional period ending 31 December 2026.
• B2G e-invoicing is already mandatory under a separate public-procurement framework using Peppol, EN 16931, the Greek CIUS and the National Interoperability Centre.
• The new B2B obligation applies principally to domestic B2B transactions, specified B2G transactions and sales to customers established outside the EU. Invoices to EU-established business customers remain outside the compulsory domestic e-invoicing scope for the moment, although the underlying transaction must still be reported through myDATA where Greek reporting rules apply.
• The legally permitted issuance routes under the mandatory B2B framework are an AADE-licensed e-invoicing provider or AADE’s free timologio application. A direct ERP-to-myDATA reporting connection, by itself, should not be treated as a substitute for the prescribed electronic-issuance channel once the mandate applies.
• Greece already uses myDATA data to pre-fill VAT returns. Since 2025, the permitted deviation between relevant VAT-return amounts and myDATA data has effectively been reduced to zero, making upstream invoice and classification accuracy critical. [ey.com], [aade.gr], [sovos.com]

The distinction between e-invoicing and e-reporting is essential. myDATA reporting is broader than the 2026 structured e-invoicing mandate. A transaction may remain reportable to myDATA even where Greece does not require the commercial invoice exchanged with the customer to be a mandatory structured e-invoice.

1. Introduction and Country Context

1.1 Greece’s tax-digitalisation journey

Greece introduced myDATA, meaning “My Digital Accounting and Tax Application,” as a central electronic-books platform through which businesses transmit summaries of revenue and expense documents and the related accounting or tax classifications. The system supports two electronic books maintained by AADE: a summary book and an analytical-record book. It has progressively become the central data source for VAT returns, income-tax reporting, invoice verification and digital monitoring. [aade.gr], [aade.gr], [winsightco…sulting.gr]

The country’s development can be divided into four broad stages:

• Introduction and gradual implementation of myDATA transaction reporting and electronic books.
• Rollout of B2G structured e-invoicing, with invoices exchanged through the Peppol infrastructure.
• Introduction of mandatory structured domestic B2B e-invoicing under Law 5222/2025.
• Expansion toward integrated invoice, VAT-return and digital-goods-movement controls, in parallel with the EU’s ViDA reforms. [eur-lex.europa.eu], [peppol.org], [aade.gr]

1.2 Policy rationale

The principal objectives are:

• Accelerating the detection of non-declared or under-declared VAT.
• Combating carousel and other transaction-based fraud.
• Improving the timeliness and quality of tax-authority data.
• Automating electronic books and VAT-return preparation.
• Reducing duplicate reporting and administrative errors.
• Digitally monitoring invoice issuance and, increasingly, movements of goods. [eur-lex.europa.eu], [eur-lex.europa.eu]

The EU authorising decision specifically noted that direct transmission of e-invoice data into myDATA would provide higher-quality information in real time, facilitate fraud detection and support pre-filled VAT returns. [eur-lex.europa.eu], [eur-lex.europa.eu]

1.3 Position relative to other EU countries

Greece is an early adopter of broad transaction-level VAT reporting and is now moving from reporting-only controls toward mandatory structured invoicing. Its model is best characterised as a hybrid CTC framework:

• For B2B, AADE receives and validates invoice data and assigns a unique registration number, but the supplier or its provider remains responsible for delivery to the customer.
• For B2G, the process adds a structured Peppol exchange layer through the Greek public-sector interoperability infrastructure.
• Separate reporting and classification obligations continue through myDATA. [aade.gr], [peppol.org], [gsis.gr]

1.4 EU derogation

Greece obtained EU Council authorisation through Council Implementing Decision (EU) 2025/502 of 5 March 2025, published on 13 March 2025. The decision authorised a derogation from Articles 218 and 232 of Directive 2006/112/EC, permitting Greece to require e-invoices for transactions between taxable persons established in Greece without making the requirement dependent on recipient consent. [eur-lex.europa.eu], [eur-lex.europa.eu]

The derogation applies from 1 July 2025 until 31 December 2027. After the entry into force of the ViDA changes, Member States have a broader legal basis to introduce domestic e-invoicing obligations without obtaining an individual Article 395 derogation. [eur-lex.europa.eu]

2. Regulatory Framework

2.1 Primary legislation

The principal statutory instruments are:

• Law 4308/2014, the Greek Accounting Standards law. Article 14 contains the invoicing framework.
• Law 5222/2025, which amended Article 14 of Law 4308/2014 and established mandatory electronic invoicing for the relevant transactions.
• Law 4172/2013, Article 71Θ or 71I depending on the transliteration used, which provides tax incentives for qualifying early adoption.
• The Greek Tax Procedure Code and associated penalty provisions governing failure to issue valid documents or transmit information. [ey.com], [ey.com], [zoneandco.com]

2.2 Implementing decisions

Decision A.1128/2025

AADE Decision A.1128/2025 of 15 September 2025 determines:

• The entities and transactions covered.
• The permitted issuance methods.
• The two implementation phases.
• Transitional arrangements.
• The compulsory acceptance of qualifying domestic e-invoices.
• The relationship with B2G invoicing. [ey.com], [aade.gr]

Decision A.1129/2025

Decision A.1129/2025 governs:

• Declarations for using an e-invoicing provider or timologio.
• Procedures and deadlines for electing exclusive electronic issuance.
• Conditions for the early-adoption tax incentives. [ey.com]

Decision A.1044/2026

Joint Decision A.1044/2026, published in Government Gazette B 880/17 February 2026:

• Postponed Phase 1 from 2 February to 2 March 2026.
• Extended Phase 1’s adaptation period through 3 May 2026.
• Did not change the Phase 2 commencement date of 1 October 2026. [kpmg.com], [ey.com]

Circular E.2004/2026

AADE Circular E.2004/2026 clarifies the penalty consequences of failure to comply with mandatory e-invoicing, including the treatment of an invoice issued outside an authorised channel as not validly issued for penalty purposes. [ey.com]

2.3 Official guidance and FAQs

AADE maintains:

• A dedicated myDATA portal.
• Operational specifications.
• Technical API versions and XSD schemas.
• FAQs on mandatory e-invoicing and digital goods-movement documents.
• A registry and certification framework for electronic-invoicing providers.
• timologio and myDATAapp guidance. [aade.gr], [aade.gr], [aade.gr], [aade.gr]

2.4 Supranational framework

Relevant EU instruments include:

• Directive 2006/112/EC, particularly Articles 218 and 232.
• Council Implementing Decision (EU) 2025/502.
• Directive 2014/55/EU for public-sector e-invoicing.
• EN 16931 for structured electronic invoices.
• The ViDA legislative package adopted in March 2025. [eur-lex.europa.eu], [peppol.org], [ec.europa.eu]

3. Scope of the Mandate

3.1 Domestic B2B

Mandatory structured e-invoicing applies to sales of goods and supplies of services:

• Made within Greece.
• By an entity subject to Greek Accounting Standards.
• To another entity subject to Greek Accounting Standards.

For in-scope transactions, a paper invoice or ordinary PDF generated outside an authorised channel is no longer sufficient as the legally issued invoice once the relevant mandatory period and transition arrangements have ended. A visual PDF may still accompany the structured invoice, but it does not replace the prescribed electronic issuance. [ey.com], [ey.com], [zoneandco.com]

Recipients subject to the Greek domestic framework must accept qualifying electronic invoices. The recipient-consent principle that traditionally applied under Article 232 of the VAT Directive does not prevent Greece from imposing this domestic requirement because of the EU derogation and subsequent ViDA changes. [eur-lex.europa.eu], [wts-global.com]

3.2 Domestic B2G

B2G e-invoicing is mandatory under a separate but connected framework. Public-sector invoices use:

• EN 16931.
• Peppol BIS Billing 3.0.
• The Greek national CIUS.
• Peppol eDelivery.
• The National Interoperability Centre, or KED.
• myDATA reporting and fiscal identifiers. [peppol.org], [gsis.gr], [ec.europa.eu]

Public-contract e-invoicing was introduced progressively. Current European Commission materials indicate that Greek contracting authorities receive structured invoices for covered public contracts, generally including contracts above EUR 2,500, depending on the applicable procurement rules and commencement date of the award procedure. Other General Government expenditure has also been progressively incorporated. [theinvoicinghub.com], [ec.europa.eu]

3.3 Domestic B2C

The 2026 B2B mandate does not generally convert retail receipts into B2B structured invoices. B2C transactions remain governed primarily by:

• Fiscal electronic mechanisms or compliant retail systems.
• Receipt issuance requirements.
• Real-time or near-real-time transmission to myDATA.
• QR-code and payment-interconnection rules where applicable.

Therefore, B2C is generally outside the new structured B2B e-invoicing obligation but not outside Greece’s digital fiscal-reporting environment. [aade.gr], [theinvoicinghub.com]

3.4 Intra-EU supplies

Invoices issued to businesses established elsewhere in the EU remain optional under the 2026 domestic e-invoicing mandate. The supplier must nevertheless:

• Issue a VAT-compliant invoice.
• Report the transaction to myDATA.
• Apply the appropriate intra-Community VAT classification.
• Submit VIES recapitulative information where required.

VIES forms F4 and F5 are generally due by the 26th day of the month following the transaction. [kpmg.com], [aade.gr]

3.5 Intra-EU acquisitions

An invoice received from a supplier established in another EU Member State is not transformed into a Greek mandatory B2B e-invoice. The Greek recipient must report or classify the acquisition in myDATA under the relevant acquisition-document and VAT categories and account for acquisition VAT. [aade.gr], [aade.gr]

3.6 Exports and sales to non-EU customers

Wholesale transactions with customers established outside the EU are included in the mandatory issuance scope, except retail transactions. Export invoices must therefore be issued using the applicable authorised electronic-invoicing route when the supplier is within the relevant implementation phase. [ey.com], [ey.com]

Exports remain zero-rated where the substantive VAT conditions and export evidence are met. The e-invoice and myDATA record must use the appropriate VAT-exemption or zero-rating categorisation.

3.7 Imports and foreign purchase invoices

Customs import documents and foreign supplier invoices are not Greek supplier-issued domestic e-invoices. The Greek purchaser must record and classify the import or foreign purchase through myDATA using the appropriate document type and tax treatment. Customs documentation remains essential for import VAT deduction.

3.8 Other cross-border B2B transactions

The key distinction is:

• Customer outside the EU: mandatory e-invoice issuance is generally included.
• Customer in another EU Member State: e-invoice issuance remains optional under the national 2026 mandate.
• Inbound foreign supplier invoice: not reissued through the Greek B2B platform, but the Greek recipient has myDATA accounting and classification obligations. [ey.com], [kpmg.com]

3.9 Self-billing and settlement documents

The obligation expressly extends to transactions:

• With persons not obliged to issue an invoice.
• With persons who refuse or fail to issue an invoice.
• For which a clearance or settlement note is issued.
• Involving sales on behalf of third parties. [ey.com], [wts-global.com]

AADE’s technical documentation includes a specific XML example for a sales invoice with self-billing, confirming that the myDATA schema supports this scenario. [aade.gr]

3.10 Triangulation, chain transactions and special regimes

No separate platform exclusion has been identified for triangulation, chain transactions, margin schemes, travel-agent transactions or similar regimes. The obligation depends primarily on:

• The status and establishment of the issuer.
• The customer’s location and status.
• The place and nature of the transaction.
• Whether the relevant document is one that must be electronically issued.
• The correct myDATA document type, VAT category and tax classification.

Special VAT treatment does not itself remove the document from myDATA. However, the invoice must carry the correct legal notation and exemption or special-scheme coding.

4. Taxable Persons in Scope

4.1 Established entities

The mandate applies to entities covered by Article 1 of Law 4308/2014, including, depending on their legal and accounting status:

• Companies and partnerships.
• Sole traders and professionals.
• Greek permanent establishments or branches.
• Other entities required to keep records under Greek Accounting Standards.

The two phases are based on 2023 gross revenue, but Phase 2 is not a permanent small-business exemption. It brings the remaining liable entities into scope. [aade.gr], [beancount.io]

4.2 Non-established VAT registrations

The EU derogation was requested for transactions between taxable persons established in Greece, and the national rules refer to entities subject to Greek Accounting Standards. Consequently, a foreign business merely holding a Greek VAT number, without a Greek establishment or branch subject to the Greek Accounting Standards, should not automatically be assumed to fall within the mandatory domestic issuance population.

Nevertheless:

• A non-established registration may have myDATA reporting obligations for Greek transactions.
• A Greek fixed establishment or branch may fall in scope in its own right.
• The position should be verified transaction by transaction, particularly where a foreign entity issues invoices using a Greek VAT number. [eur-lex.europa.eu], [winsightco…sulting.gr]

4.3 Foreign entities without Greek registration

A foreign entity without a Greek establishment or VAT registration is not a Greek issuer under the domestic mandate. If it supplies a Greek public authority under an in-scope public contract, however, the foreign B2G supplier may have to use Peppol and a certified service provider in accordance with the foreign-supplier instructions. [gsis.gr]

4.4 Voluntary participation

Voluntary use existed before the mandate and remains relevant for:

• Transactions not legally subject to mandatory issuance.
• Businesses adopting ahead of their mandatory date.
• Intra-EU invoices where the recipient agrees to electronic exchange.
• Entities choosing a provider-based model to obtain operational standardisation.

Early-adoption incentives included enhanced depreciation and increased deductions, provided the statutory timing and exclusivity requirements were met. [kpmg.com], [kpmg.com]

4.5 Sector-specific rules

No general sector-based exclusion from the B2B mandate has been identified in the current core materials. Sectoral transactions may nevertheless be subject to:

• VAT exemptions.
• Special invoice content.
• Special public-procurement rules.
• Regulated fiscal-document requirements.
• Simplified retail or transport-document rules.

5. Implementation Timeline

5.1 Earlier myDATA and B2G milestones

• 2020: myDATA introduced with voluntary or preparatory operation.
• 2021 onward: transaction-reporting obligations progressively became operational.
• January 2022: Greek B2G e-invoicing infrastructure entered production.
• 2023 to 2025: B2G supplier obligations were phased by contracting-authority and procurement category.
• 5 December 2022 onward: VAT returns concerning periods from 1 January 2022 began displaying myDATA-based pre-filled amounts. [aade.gr], [peppol.org], [ec.europa.eu]

5.2 EU and national legislative milestones

• 2 July 2024: Greece’s derogation request was registered by the European Commission.
• 5 March 2025: Council Implementing Decision (EU) 2025/502 adopted.
• 13 March 2025: Decision published in the Official Journal.
• July 2025: Law 5222/2025 enacted.
• 15 September 2025: Decision A.1128/2025 issued.
• September 2025: Decision A.1129/2025 issued.
• 17 February 2026: Decision A.1044/2026 published, postponing Phase 1. [eur-lex.europa.eu], [ey.com], [aade.gr]

5.3 Phase 1

Phase 1 covers entities whose gross revenue for fiscal year 2023 exceeded EUR 1 million:

• Mandatory start: 2 March 2026.
• Transitional adaptation: 2 March through 3 May 2026.
• During transition, other pre-existing issuance methods could continue under the prescribed conditions, notably timely submission of the relevant declaration. [kpmg.com], [ey.com]

5.4 Phase 2

Phase 2 covers the remaining liable entities:

• Mandatory start: 1 October 2026.
• Transitional adaptation: 1 October through 31 December 2026.
• Full exclusive application after the transition: 1 January 2027.
• Access to the transition is conditional on satisfying the applicable declaration requirements rather than being an unconditional waiver. [eu-einvoicing.com], [beancount.io], [peppol.nu]

As at 6 October 2026, Phase 2 has commenced, but businesses within the valid transition arrangement may continue a controlled parallel rollout until 31 December 2026.

5.5 Early-adoption incentives

Qualifying early adopters could receive:

• A 100% uplift in depreciation for qualifying e-invoicing equipment and software.
• A 100% uplift in deductible expenditure connected with invoice production, transmission and electronic archiving for the prescribed period.

The incentive required adoption sufficiently before the mandatory start date and compliance with the declaration and exclusivity conditions. [kpmg.com], [kpmg.com]

5.6 Postponement risk

Phase 1 was postponed once, from 2 February to 2 March 2026. No enacted postponement of the 1 October 2026 Phase 2 start was identified in the sources reviewed up to 6 October 2026. The transition through 31 December 2026 should not be described as a general postponement.

6. Operating Model

6.1 Model classification

The B2B framework is best described as a hybrid real-time issuance and reporting model, rather than a pure government-delivery clearance model:

• The invoice is issued through a licensed provider or timologio.
• Core invoice data are transmitted to myDATA.
• myDATA performs technical and basic fiscal checks.
• A unique MARK is assigned.
• A QR code or verification reference supports authenticity checking.
• The invoice is delivered to the buyer by the provider or issuer rather than necessarily being routed by AADE as a central exchange hub. [aade.gr], [aade.gr]

B2G follows a more explicit interoperability model through Peppol and KED.

6.2 Invoice lifecycle

Step 1: Creation

The supplier creates the invoice using:

• Licensed provider software integrated with its ERP, or
• AADE’s timologio application.

The invoice contains normal statutory VAT data plus myDATA document types, VAT categories, income classifications and other Greek fiscal information.

Step 2: Submission

The provider or timologio transmits the invoice information to myDATA in real time. The provider is responsible for automatic transmission immediately after issuance. [aade.gr]

Step 3: Validation

myDATA performs:

• XML and schema validation.
• Taxpayer and document-type validation.
• Mandatory-field checks.
• VAT-category and classification checks.
• Arithmetic and consistency controls.

If the submission fails, the system returns an error rather than a successful registration. The source system must correct the cause and resubmit.

Step 4: Registration

A successfully transmitted document receives a MARK, the Unique Registration Number. Provider-issued invoices also use a QR code that permits verification of authenticity and registration. [aade.gr], [aade.gr]

Step 5: Delivery

For B2B, the issuer or provider delivers the validated invoice to the customer using the agreed electronic method. For B2G, the Peppol provider transmits the authoritative XML through an AS4 Access Point to the common Greek public-sector endpoint. [gsis.gr]

Step 6: Buyer processing

The buyer imports the document, validates commercial details, books the expense and transmits or confirms the relevant expense classification. A buyer’s commercial dispute or rejection does not erase the supplier’s initial myDATA submission.

Step 7: Archiving

The issuer and recipient must retain the relevant invoice and audit evidence. Provider or platform storage should not be assumed to eliminate the taxpayer’s legal retention responsibility.

6.3 Authentication

AADE REST interfaces use registered myDATA credentials, including usernames and subscription keys. Providers have separate certification, authentication and software-licensing requirements. B2G transmission uses certified Peppol service providers and AS4 infrastructure. [aade.gr], [gsis.gr]

6.4 Contingency mode

The current sources confirm transitional parallel issuance and technical interfaces for cancellations and corrections, but they do not establish a universal, unrestricted “offline invoice” exception for the mandatory B2B regime. Businesses should therefore:

• Implement queueing and automated retry.
• Preserve evidence of AADE or provider downtime.
• Use the contingency procedure specified by their licensed provider.
• Resubmit within the applicable technical deadline.
• Avoid inventing or manually assigning a MARK.

6.5 Buyer acceptance

Domestic recipients are required to accept qualifying e-invoices. This legal acceptance obligation should not be confused with commercial approval. Buyers may still reject an invoice commercially because of pricing, quantity, purchase-order or contractual errors. [wts-global.com], [eur-lex.europa.eu]

6.6 QR codes

Provider-issued e-invoices include a QR code or verification mechanism allowing the document’s authenticity and platform registration to be checked. The QR mechanism supplements, but does not replace, the structured invoice and MARK. [aade.gr]

7. Acceptable E-Invoice Formats

7.1 B2B format

For B2B, the tax-facing transmission uses the myDATA XML schema and AADE data model. It includes:

• Issuer and counterparty information.
• Invoice header and numbering data.
• Line-level values.
• VAT rates and categories.
• Withholding taxes, stamp duties and other taxes where relevant.
• Payment-method information.
• Income and expense classifications.
• References to related documents.
• MARK, cancellation-mark and related platform identifiers. [aade.gr], [aade.gr]

References in some advisor materials to EN 16931 should not be interpreted as meaning that every B2B invoice uses the Greek B2G Peppol CIUS. The tax-reporting payload remains based on AADE’s myDATA schema, while B2G has a clearly defined EN 16931 and Peppol BIS format.

7.2 B2G format

The authoritative B2G invoice is:

• Structured XML.
• Compliant with EN 16931.
• Based on Peppol BIS Billing 3.0.
• Adapted through the Greek CIUS.
• Transmitted through Peppol by a certified service provider. [peppol.org], [gsis.gr]

The Greek government’s instructions for foreign suppliers expressly state that the XML document is the legally authoritative B2G invoice. [gsis.gr]

7.3 PDF and paper

• For mandatory B2B transactions, a standalone PDF or paper document is not the prescribed electronic invoice after the applicable transition.
• A human-readable PDF rendition may be supplied for convenience and verification.
• For transactions outside the mandatory e-invoicing scope, such as certain intra-EU invoices, existing VAT-compliant formats may continue, subject to myDATA reporting.
• B2C receipts remain governed by the retail fiscal-document rules rather than the B2B XML mandate.

7.4 Attachments

The public sources reviewed do not establish a general rule making commercial attachments part of the tax-reporting payload. Purchase orders, timesheets, delivery evidence and supporting PDFs may be exchanged separately or through provider functionality. For B2G, attachment handling must comply with the Peppol BIS and Greek CIUS technical rules.

8. Technical and Functional Requirements

8.1 Invoice data

Core information includes:

• Document series and sequential number.
• Document type.
• Issue date.
• Supplier name, address and tax number.
• Customer name, address and tax number, where required.
• Country and establishment identifiers.
• Goods or service description.
• Quantity and unit price.
• Net amount.
• VAT category and rate.
• VAT amount.
• Exemption or reverse-charge reason.
• Withholding and other taxes.
• Gross and payable amount.
• Currency.
• Payment method.
• Related invoice references for credit notes.
• myDATA income classification.
• Self-billing, third-party-sale or settlement indicators where relevant. [aade.gr], [aade.gr]

8.2 E-reporting data

myDATA reporting covers more than the invoice itself:

• Revenue-document summaries.
• Expense-document summaries or recipient records.
• Income classifications.
• Expense classifications.
• Accounting-settlement records.
• Payroll and depreciation records where applicable.
• Payment-method records.
• VAT and withholding information.
• Goods-movement information under the separate digital-delivery framework. [aade.gr], [aade.gr]

8.3 Validation

Validations include:

• XSD conformity.
• Mandatory identifiers.
• Permitted document-type combinations.
• Valid VAT categories and rates.
• Mathematical consistency.
• Referencing of original documents for correlated credit notes.
• Valid classification combinations.
• Duplicate or cancellation controls.

AADE version 2.0.2 introduced and refined document types, cancellation functions, movement-document functionality and request methods. Businesses should use the current AADE XSDs and code lists rather than hard-code an older schema version. [aade.gr]

8.4 Signature and integrity

The materials reviewed do not indicate a universal requirement for a separate qualified electronic signature on every B2B invoice. Integrity and authenticity are principally supported by:

• Issuance through a licensed provider or AADE application.
• Platform registration.
• MARK.
• QR-code verification.
• Provider controls and audit trail.
• Secure transmission and retention. [aade.gr], [aade.gr]

B2G authenticity and transport security are additionally supported through Peppol service-provider and AS4 controls.

8.5 Processing speed

Provider-issued income documents are transmitted in real time and automatically after issuance. Other myDATA records may have transaction-specific reporting deadlines. The regime should therefore not be implemented as a month-end batch-only process. [aade.gr]

9. Correction of Errors

9.1 E-invoice corrections

A registered invoice should not simply be overwritten. Corrections are handled through:

• Cancellation, where the platform rules permit cancellation and no replacement commercial transaction is required.
• A correlated credit note referencing the original invoice.
• A debit or replacement invoice where required.
• Resubmission of a rejected document after correcting schema or data errors.

AADE’s technical specifications contain interfaces such as CancelInvoice and examples of correlated credit notes. [aade.gr], [aade.gr]

A corrective document should include:

• Reference to the original invoice or MARK where required.
• Reason for correction.
• Corrected taxable amount.
• Correct VAT category, rate and VAT amount.
• Correct income classification.
• Linkage to the original commercial transaction.

9.2 E-reporting corrections

myDATA errors may require:

• Cancellation and retransmission.
• A corrective accounting entry.
• Corrected income or expense classification.
• Counterparty deviation or rejection processing.
• An amended VAT return if the original VAT return has already been filed.
• A corrective VIES statement for affected intra-EU transactions.

The AADE VAT portal permits initial and amending periodic VAT returns and corrective VIES statements. [aade.gr]

9.3 Timing

Corrections should be made before the VAT filing deadline wherever possible. This is particularly important because pre-filled VAT-return fields now closely follow myDATA, and businesses can no longer rely on broad manual overrides to resolve invoice-level errors at return stage. [sovos.com]

10. Transmission and Workflow

10.1 Central platform

The central tax-reporting platform is myDATA, operated by AADE.

10.2 Permitted issuance routes

For mandatory B2B issuance, the core routes are:

• An AADE-licensed electronic-invoicing provider.
• AADE’s free timologio application.

myDATAapp may provide mobile functionality for relevant businesses. However, ordinary ERP reporting directly to myDATA should not be regarded as an independent authorised B2B issuance channel once the exclusive mandatory-invoicing rules apply. The ERP can remain the source system, but it should connect to the provider or relevant AADE issuance application. [ey.com], [aade.gr], [wrapp.ai]

10.3 Providers

Provider use is optional where timologio is operationally suitable. For larger businesses, provider integration is likely to be the practical route because it supports:

• High invoice volumes.
• ERP integration.
• Real-time submission.
• MARK and QR-code processing.
• Customer delivery.
• Status and error management.
• Archiving services.

AADE publishes provider information and explains that providers transmit invoices in real time under their own responsibility. [aade.gr]

10.4 Peppol

Peppol is central to B2G but is not identified as the universal B2B delivery network. For B2G:

• The supplier uses a certified Peppol service provider.
• The structured document is transmitted through an AS4 Access Point.
• The common Greek contracting-authority endpoint is hosted at KED.
• Public-body processing statuses can be returned through the infrastructure. [peppol.org], [gsis.gr]

10.5 Deadlines

Key timing rules include:

• Provider-issued revenue invoices: real-time transmission.
• VAT returns: by the last business day of the following month or quarter, depending on the taxpayer’s filing period.
• VIES recapitulative statements: generally by the 26th of the following month.
• Classification and accounting-adjustment records: according to the applicable myDATA annual and return-cycle deadlines.
• Corrections: before return submission wherever possible. [aade.gr], [aade.gr]

11. Self-Billing

11.1 Permitted status

Self-billing is permitted, subject to the legal conditions governing invoices issued by the customer on behalf of the supplier.

11.2 Platform treatment

Where the underlying transaction is within the mandatory scope, the self-billed invoice must be handled through the relevant electronic-invoicing and myDATA process. AADE’s technical materials include a specific self-billing XML example. [aade.gr]

11.3 Required controls

Businesses should maintain:

• A prior self-billing agreement.
• A documented supplier-approval or acceptance procedure.
• Correct identification of the legal supplier and customer.
• A self-billing indicator or applicable document mapping.
• Correct attribution of revenue to the supplier.
• Correct myDATA classifications.
• A process for rejected or disputed invoices.

11.4 Foreign buyers

Where the self-billing customer is foreign and lacks a Greek tax identifier, the technical and legal configuration must be assessed carefully. The public materials reviewed do not provide a universal rule for every foreign-buyer self-billing configuration. The parties should confirm:

• Which entity is legally issuing the invoice.
• Whether the supplier is in a mandatory Greek issuance phase.
• Whether the transaction is domestic, intra-EU or non-EU.
• Which party or authorised provider transmits the document.
• How foreign identifiers are populated in the schema.

12. Triangulation and Special Scenarios

12.1 Triangulation

For an EU triangulation:

• The Greek intermediary’s purchase and onward supply must be separately classified.
• The inbound supplier invoice is not a domestic Greek structured e-invoice.
• The Greek intermediary’s intra-EU onward invoice remains outside the compulsory domestic B2B e-invoicing scope but remains reportable.
• VIES reporting and the triangulation notation remain necessary.

12.2 Chain transactions

Each legal supply in a chain must be analysed independently. The decisive factors include:

• Which supply is the moving supply.
• Customer establishment.
• VAT registration used.
• Place of supply.
• Domestic versus intra-EU or export treatment.
• Which entity has the Greek invoicing obligation.

Physical movement of goods does not by itself determine whether the invoice is within the domestic structured mandate.

12.3 Reverse charge

For outbound reverse-charge invoices:

• The correct VAT category must be used.
• The invoice must include the required reverse-charge wording or code.
• The appropriate myDATA classification must be applied.

For inbound foreign reverse-charge invoices:

• The foreign supplier’s invoice is recorded by the Greek recipient.
• The Greek recipient reports the expense and self-accounts for VAT where required.
• Both output and deductible input tax are reflected subject to deduction entitlement.

12.4 Zero-rated and exempt supplies

Zero-rated or exempt transactions remain reportable. The invoice and myDATA entry should include:

• The correct VAT category.
• Zero VAT amount.
• Relevant exemption or legal-basis indication.
• Correct income classification.
• Customs or transport evidence where needed.

12.5 Margin and travel-agent schemes

The margin or special-scheme VAT treatment must be reflected in the invoice wording and accounting classification. The public sources reviewed do not identify a general exclusion of these transactions from myDATA or mandatory issuance merely because a margin scheme applies.

13. Archiving and Retention

13.1 Taxpayer responsibility

myDATA stores transmitted tax data, and providers may preserve copies, but this should not be treated as a complete substitute for the taxpayer’s statutory archive. The business should retain:

• The original structured invoice.
• Human-readable representation where used.
• MARK and QR or verification data.
• Transmission and acknowledgement records.
• Credit notes and cancellations.
• Supporting commercial and delivery documentation.
• Evidence of authenticity, integrity and readability.

13.2 Format

For B2B, the prudent retention standard is the original provider-issued electronic record and associated structured myDATA data. For B2G, the authoritative Peppol XML must be preserved. A PDF alone should not be considered an adequate substitute for the authoritative structured document. [gsis.gr]

13.3 Retention period

Recent advisor summaries generally cite a minimum six-year retention period for Greek invoices. Longer retention may be appropriate where:

• The tax-assessment period is extended.
• Litigation or an audit is pending.
• Loss carryforwards, subsidy claims or long-term assets are involved.
• Other accounting or commercial laws require longer storage. [theinvoicinghub.com]

13.4 Storage location

The reviewed current sources do not identify an absolute domestic-only storage rule. EU or third-country cloud storage should be acceptable only where:

• AADE receives timely online access on request.
• Data remain readable and exportable.
• Authenticity and integrity are maintained.
• GDPR and international data-transfer requirements are met.
• The business can reproduce the original structured records without dependence on an unavailable provider.

13.5 Audit access

Records must be retrievable promptly and linked to the statutory books, VAT returns and myDATA submissions. Businesses should be able to provide both human-readable and machine-readable evidence.

14. Penalties and Enforcement

14.1 Core consequence

Failure to use the mandatory electronic issuance method may be treated as failure to issue the required tax document, rather than as a minor technical reporting defect. Circular E.2004/2026 is the key current interpretative source. [ey.com]

14.2 VAT-bearing transactions

Advisor summaries of the 2026 rules report a penalty of up to 50% of the VAT associated with the non-compliant transaction where an invoice that should have been electronically issued is issued outside the required framework. [eu-einvoicing.com], [beancount.io]

14.3 Transactions without VAT

For transactions not carrying VAT, fixed penalties reported in current guidance are generally:

• EUR 500 for taxpayers using simplified accounting books.
• EUR 1,000 for taxpayers using double-entry books.

The application should be checked against the exact taxpayer category and current Tax Procedure Code wording before determining exposure. [eu-einvoicing.com], [winsightco…sulting.gr]

14.4 myDATA transmission penalties

Separate penalties may apply for:

• Failure to transmit revenue data.
• Late transmission.
• Failure to transmit expense classifications.
• Incorrect values.
• Failure to transmit digital movement documents.
• Repeat infringements.

Greek penalty rules have included percentage-based penalties for omitted or incorrect transaction data, reduced penalties for late transmission and escalation for repeated violations. [vatupdate.com]

14.5 Indirect consequences

Potential consequences also include:

• Expense or input-VAT mismatches.
• Challenges to the purchaser’s VAT deduction or corporate-tax deductibility.
• VAT-return discrepancies.
• Audit flags.
• Delayed invoice processing and payment.
• Reconciliation problems between ERP, provider, customer and myDATA.
• Loss of early-adoption incentives.

14.6 Transitional enforcement

Phase 2’s period through 31 December 2026 provides operational adaptation under specified conditions. It is not a blanket immunity from all myDATA, VAT, invoice-issuance or declaration penalties.

15. Pre-Filled VAT Returns

15.1 Current status

Greece already provides pre-filled periodic VAT returns. For returns submitted from 5 December 2022 concerning periods from 1 January 2022, relevant fields are populated using transaction data and classifications transmitted to myDATA. [aade.gr]

15.2 Data sources and fields

Pre-filling is based principally on:

• Reported taxable outputs.
• VAT on outputs.
• Reported purchases and expenses.
• Deductible input VAT information.
• myDATA revenue and expense classifications.

Taxpayers must still review:

• Deduction restrictions.
• Partial-exemption calculations.
• Capital-goods adjustments.
• Reverse-charge accounting.
• Imports.
• Corrections and prior-period adjustments.
• Transactions not fully represented by supplier-issued domestic documents.

15.3 Ability to amend

AADE’s general portal description states that taxpayers can modify pre-filled amounts. However, subsequent measures have progressively restricted permissible deviations, and advisor analysis reports a zero-deviation limit from January 2025 for the relevant pre-filled VAT-return amounts. In practice, discrepancies should be corrected upstream in myDATA rather than overridden only in the return. [aade.gr], [sovos.com]

15.4 Operational implication

The VAT return is increasingly the output of transaction-level compliance. Businesses therefore need reconciliation between:

• Sales and purchasing ledgers.
• Provider records.
• myDATA summary and classifications.
• Customs records.
• VIES.
• Periodic VAT return.

16. ViDA Readiness

16.1 Position relative to ViDA

Greece is ahead of the 1 July 2030 ViDA cross-border Digital Reporting Requirements in terms of operating a domestic real-time reporting platform. However, the current Greek model and ViDA are not identical.

Greece already has:

• Transaction-level reporting.
• Structured domestic e-invoicing.
• Tax-authority invoice identifiers.
• Pre-filled VAT returns.
• A Peppol-based B2G infrastructure.

ViDA will require harmonised intra-EU structured invoicing and digital reporting from 1 July 2030, replacing current recapitulative statements for affected transactions. [eur-lex.europa.eu], [e-invoice.app]

16.2 Alignment strengths

Strengths include:

• Existing real-time infrastructure.
• Mature tax-classification model.
• Experience with structured public invoices.
• EN 16931 and Peppol capability in B2G.
• Established APIs and provider ecosystem.
• Existing use of data for pre-filled returns.

16.3 Alignment gaps

Potential adjustments include:

• Ensuring the domestic B2B semantic model is fully interoperable with EN 16931.
• Avoiding duplicative reporting when ViDA cross-border DRR begins.
• Supporting intra-EU invoice exchange without national-specific fragmentation.
• Aligning correction, status and identifier rules.
• Converting current intra-EU reporting from VIES to ViDA’s transaction-level architecture.
• Ensuring that national clearance or reporting controls do not obstruct cross-border interoperability.

16.4 Business implications

A future-proof implementation should separate:

• Core EN 16931 invoice data.
• Greek myDATA extensions and classifications.
• Customer-delivery format.
• Peppol transport layer.
• Tax-authority reporting layer.

This reduces the risk that a Greece-specific solution must be rebuilt for ViDA.

17. Impact on SMEs and Startups

17.1 Phased onboarding

SMEs and microbusinesses largely fall into Phase 2:

• Mandatory commencement: 1 October 2026.
• Transitional adaptation: through 31 December 2026.
• Full exclusivity: from 1 January 2027, subject to the exact transitional conditions. [eu-einvoicing.com], [beancount.io]

This is a deferral by taxpayer size, not a permanent SME exemption.

17.2 Free tools

AADE provides:

• timologio.
• myDATAapp.
• The myDATA portal.
• APIs and technical documentation.
• Test environments and published schemas.
• FAQs and support channels. [aade.gr], [aade.gr], [aade.gr]

These tools reduce entry costs for businesses with low invoice volumes but may be less suitable for complex order-to-cash, high-volume or multi-entity environments.

17.3 Simplifications and thresholds

The EUR 1 million threshold determined timing only. It does not create a general exemption after Phase 2. Smaller businesses may benefit operationally from free tools and simpler deployment routes rather than reduced substantive obligations.

17.4 Financial support

The principal identified support is the early-adoption tax incentive:

• Enhanced depreciation for relevant equipment and software.
• Increased deduction for qualifying issuance, transmission and archiving expenditure.

These incentives depended on timely adoption before the applicable compulsory date. [kpmg.com], [kpmg.com]

17.5 Costs

Likely one-time costs include:

• ERP mapping.
• Provider onboarding.
• Master-data cleansing.
• Invoice-template adaptation.
• API integration.
• User training.
• Process and control redesign.
• Testing of credit notes, self-billing and cross-border scenarios.

Ongoing costs may include:

• Provider fees.
• Support and maintenance.
• Schema upgrades.
• Archive management.
• Exception handling.
• Monitoring and reconciliation.

17.6 Benefits

Potential benefits include:

• Automated posting.
• Fewer manual invoice errors.
• Faster customer validation.
• Earlier identification of VAT mismatches.
• Improved audit trails.
• Better VAT-return reconciliation.
• Reduced paper handling.
• Greater payment-status visibility in B2G.

17.7 Net administrative effect

For very small businesses, the short-term burden is significant because invoicing moves from familiar PDF or paper processes to controlled digital issuance. Over time, the combination of free tools, automatic myDATA transmission and pre-filled returns may reduce duplicate work, provided the business maintains accurate product, customer and VAT master data.

17.8 Readiness risk

The greatest SME risks are:

• Late provider selection.
• Incorrect assumption that an existing ERP-to-myDATA reporting interface satisfies mandatory issuance.
• Failure to submit the required commencement declaration.
• Poor error-handling capacity.
• Lack of knowledge about credit-note and cancellation processes.
• Dependence on a single accountant or software supplier.

18. Official References and Sources

18.1 Government and tax-authority sources

• AADE myDATA portal
• AADE myDATA operational specifications
• AADE technical specifications and current myDATA versions
• AADE electronic-invoicing service providers
• AADE mandatory e-invoicing and digital-goods-movement FAQs
• AADE VAT and VIES returns portal
• AADE Decision A.1128/2025
• Official myDATA ERP API documentation

18.2 EU and B2G sources

• Council Implementing Decision (EU) 2025/502
• European Commission derogation proposal and explanatory memorandum
• European Commission 2025 Greece e-invoicing country sheet
• OpenPeppol Greece country profile
• Greek government instructions for foreign B2G suppliers

18.3 Advisor commentary

• EY Greece: mandatory e-invoicing framework
• EY Greece: 2026 postponement and penalties
• KPMG: original implementation timetable
• KPMG: Phase 1 postponement
• Deloitte Greece: mandatory B2B e-invoicing
• Sovos: pre-filled VAT returns
• EDICOM: updated implementation timetable

18.4 Source caveats

Some commercial sources use “clearance” to describe myDATA validation, while others describe the system as real-time reporting. The practical position is nuanced: AADE receives invoice data and returns a MARK, but ordinary B2B delivery is not necessarily performed by AADE as a central exchange platform. B2G, by contrast, has a separately defined Peppol and KED delivery workflow. [aade.gr], [peppol.org], [e-invoice.app]

Older 2025 guidance showing 2 February 2026 as the Phase 1 start is outdated. The enacted start became 2 March 2026 under A.1044/2026. [kpmg.com], [kpmg.com], [ey.com]

19. Summary and Key Takeaways

19.1 Scope

• Mandatory structured e-invoicing covers domestic B2B transactions, specified B2G transactions and wholesale supplies to non-EU customers.
• Intra-EU business invoices remain optional under the current national issuance mandate.
• B2C remains outside the B2B structured mandate but is subject to retail fiscalisation and myDATA reporting.
• Self-billing and settlement-type documents can fall within the framework.

19.2 Format

• B2B tax transmission uses the myDATA XML data model through a licensed provider or timologio.
• B2G uses EN 16931, Peppol BIS Billing 3.0 and the Greek CIUS.
• A standalone PDF is not sufficient for an in-scope mandatory structured invoice after the applicable transition.

19.3 Timeline

• Phase 1: 2 March 2026, with transition through 3 May 2026.
• Phase 2: 1 October 2026, with transition through 31 December 2026.
• Full Phase 2 operation: 1 January 2027.
• ViDA intra-EU digital reporting: 1 July 2030.

19.4 Key obligations

Businesses must be able to:

• Issue through an authorised channel.
• Transmit in real time.
• Obtain and retain the MARK.
• Deliver the electronic invoice to the customer.
• Apply correct VAT and myDATA classifications.
• Process buyer-side expense classifications.
• Correct invoices through cancellations or corrective documents.
• Reconcile myDATA with VAT returns.
• Preserve structured records and audit evidence.

19.5 Main risks

The most important risks are:

• Treating ordinary ERP-to-myDATA reporting as sufficient for mandatory issuance.
• Continuing to issue only PDFs.
• Misclassifying domestic, intra-EU and non-EU transactions.
• Missing commencement declarations.
• Failing to process rejections and corrections.
• Allowing myDATA errors to flow into effectively locked VAT returns.
• Assuming provider storage fully replaces statutory archiving.
• Failing to prepare self-billing and special-transaction workflows.

19.6 Immediate next steps as at 6 October 2026

Businesses in Phase 2 should immediately:

1. Confirm that any required commencement or transition declaration was submitted on time.
2. Select and activate either timologio or an AADE-licensed provider.
3. Validate whether the ERP is connected to an authorised issuance route, not merely to the reporting API.
4. Map domestic B2B, B2G, intra-EU, export, self-billing, credit-note and reverse-charge scenarios.
5. Test MARK retrieval, QR-code generation, rejections, cancellations and correlated credit notes.
6. Establish buyer-side invoice-retrieval and expense-classification controls.
7. Reconcile myDATA, VAT returns and VIES before each filing.
8. Preserve the original structured invoice and platform acknowledgements.
9. Prepare for the end of the Phase 2 transition on 31 December 2026.
10. Design the solution around EN 16931-compatible core data so that it can be adapted for ViDA’s cross-border requirements from 1 July 2030.