myDATA — classification, characterisation, channels

This page goes into the fine mechanics of myDATA. Beyond transmitting an invoice, the business must characterise it: state what kind of income or expense it is, via codes that point directly to the lines of the E3 tax form. Three objects structure everything: the invoice type (invoiceType), the classification (incomeClassification / expensesClassification) and the transmission channel. Aimed at integrators and tax specialists.

History — why classify

myDATA was designed not just for VAT, but to pre-build the company's tax accounts. By requiring every amount to be tied to a category of income or expense, AADE can automatically aggregate the data toward the E3 form (the business profit statement) and the VAT return. Characterisation is therefore the core of the value: without it, myDATA would be just an invoice log; with it, it is a structured accounting book.

Governance — versioned AADE schema

The myDATA schema is versioned and published by AADE (technical documentation, XSD, code lists). The invoice types, classification codes (E3_*) and categories evolve via A. decisions and version updates. The value lists (code lists) are normative: a code unknown to the current version is rejected. Integrators must therefore follow AADE's release notes and test against the pre-production environment (sandbox) before any go-live.

Schema — types, classification, characterisation

First the invoice type and VAT category, which qualify the transaction:

myDATA invoice types (invoiceType) — extracts
=============================================
1.1  Sale of goods (domestic)
1.2  Sale of goods — intra-Community supply
1.3  Sale of goods — export to third countries
2.1  Provision of services
2.2  Services — intra-Community
2.3  Services — export
3.1  Title / invoice on behalf of third parties
5.1  Credit note (pistotiko) — correlated
5.2  Credit note — non-correlated
6.1  Self-billing / internal documents
11.x Retail receipts (B2C, lianiki)
13.x / 14.x  Expenses / acquisitions without an issuing counterpart

VAT categories (vatCategory)
  1 = 24%   2 = 13%   3 = 6%   ...   7 = 0%   8 = without VAT
  vatExemptionCategory: exemption cause (article of the VAT Code)

Then the classification proper — this is what performs the characterisation and feeds the E3 form:

Classification (characterisation) — income and expenses
=======================================================
incomeClassification (issuer side — income)
  classificationType     e.g. E3_561_001 (sale of goods/merchandise),
                              E3_561_007 (provision of services)...
  classificationCategory e.g. category1_1  (sale-of-goods income),
                              category1_3  (services income)...
  amount                 amount tied to this classification

expensesClassification (receiver side — expenses)
  classificationType     e.g. E3_102_001 (purchases of merchandise),
                              E3_585_*    (various charges)...
  classificationCategory e.g. category2_1, category2_2 ...
  vatClassification      type/category of deductible VAT

Principle:
  - classificationType   = LINE of the E3 tax form
                           (business profit statement)
  - classificationCategory = accounting nature (sale of goods, services...)
  The characterisation can be done by the issuer OR completed by the
  receiver (notably on the expenses side).

XML (extract):
  <incomeClassification>
    <classificationType>E3_561_001</classificationType>
    <classificationCategory>category1_1</classificationCategory>
    <amount>1000.00</amount>
  </incomeClassification>

Transmission channels compared

myDATA accepts several channels depending on the company's size and tooling:

Application — reconciliation and E3

• Toward VAT: the vatCategory and amounts feed the summary book that reconciles with the VAT return.
• Toward profit: the classificationType (E3_*) aggregate toward the E3 form — progressive pre-filling.
• Issuer vs receiver: income characterisation is carried by the issuer; expense characterisation can be completed by the receiver.
• B2C retail: FIM cash registers report retail categories, completing transaction coverage.

Common pitfalls

• Obsolete classification code. A classificationType withdrawn in a recent schema version is rejected — follow AADE release notes.
• invoiceType inconsistent with classification. A "sale of goods" type with a "services" classification creates a detected inconsistency.
• Uncharacterised expenses. On the receiver side, omitting expense characterisation blocks E3 reconciliation and deductibility.
• Testing in production. Not validating first in the AADE sandbox leads to mass rejections and missing MARKs.
• Wrong vatExemptionCategory. An exempt transaction without the right exemption cause (article of the VAT Code) is invalid.

Cross-links

• Greece hub — full view
• myDATA — electronic books
• Accredited provider model
• VAT (FPA) regimes
• B2B mandate 2025-2026
• ViDA 2030 — DRR alignment
• AADE — myDATA documentation