What is myDATA and how do you send invoices to it

myDATA (my Digital Accounting and Tax Application) is the AADE platform that holds businesses’ electronic books. Every time you issue an invoice or receipt, its key details, issuer, recipient, amounts, VAT and type, are sent to myDATA. Your suppliers do the same for the documents they issue to you.

That way AADE sees both sides of every transaction and can cross-check them. For the business, the benefit is that its income and expenses are gathered in one place, which tax returns then build on.

myDATA is not invoicing software. It is the recipient of the data. How you issue the document, with which software or app, is your choice, within the channels AADE recognises.

When a document is transmitted successfully, myDATA replies with three things:

• MARK (ΜΑΡΚ, unique registration number): the number under which the document is entered in the e-books. Without a MARK, the document has not been registered.
• UID: a unique identifier calculated from the document’s key details (issuer VAT number, date, branch, type, series and number). It makes sure the same document cannot be registered twice.
• QR code: a link that lets anyone who scans the document verify that it was transmitted.

An ERP’s QR code is not a “mark” on the document. Where marking is required, it comes from the fiscal electronic device (ΦΗΜ) or from the authentication code of a certified provider. The QR code simply shows that the summary reached myDATA.

There are four main ways a document reaches myDATA:

• Invoicing software (ERP): your software issues the document and sends it directly through AADE’s interface.
• Certified e-invoicing provider: a company licensed by AADE marks the document, sends it to myDATA and delivers it to the recipient. This is the e-invoicing channel.
• timologio and myDATAapp: AADE’s free desktop and mobile apps, suited to businesses that issue few documents.
• Special registration form: manual entry on the portal, in the cases AADE allows.

Retail receipts from a cash register (ΦΗΜ) follow their own route to AADE.

Mandatory B2B e-invoicing changes the picture: for invoices between businesses, an ERP without a provider stops being an accepted way to issue them once the transition period ends (31 January 2027 for businesses up to €1m). From then on, B2B invoices are issued through a provider or timologio / myDATAapp.

myDATA receives income documents (invoices, receipts, credit notes), self-billing documents and entries for income or expenses where no document is issued. On the recipient’s side, the expense classifications of the documents they receive are sent as well.

Timing depends on the channel:

• Through an ERP, since 1 January 2024 (decision Α.1170/2023, amending Α.1138/2020), documents are sent in real time, at the moment of issue. If the connection drops, the document is issued with a “loss of connection” flag and sent by the next day.
• Through a provider or AADE’s apps, transmission is done by the channel itself, as the document is issued.
• Entries without a document (for example subsidies or accounting entries) usually have until the 20th of the following month.

The simplest approach is to have nothing to remember: software that transmits at the moment of issue covers you automatically.

A classification tells myDATA what kind of income or expense each line of a document is: for example, whether an invoice is for the sale of goods or for services, or whether a purchase is stock, a fixed asset or a general expense. A classification is made up of a category and a type, which map to the fields of the tax forms, such as the E3.

The issuer classifies their income when they send the document. Good invoicing software does this automatically, based on the product or service you used.

The recipient sees in myDATA the documents their suppliers issued and classifies them as expenses. This is usually handled by the accountant, but it helps a lot to already have your purchase documents recorded in your software.

If you are not sure how a type of income should be classified, set it up once with your accountant on the product or service, so it is applied correctly on every document.

A document that has a MARK is not simply “deleted”. Mistakes are corrected in a way that leaves a trail in the e-books:

• If a document was sent by mistake, for example twice or to the wrong customer, the issuer can cancel it in myDATA. The cancellation is recorded too.
• If the document was correct but something in the transaction changed, such as returned goods or a discount, a credit note is issued, sent like any other document and linked to the original.
• If the recipient spots a mistake in a document issued to them, they can flag it in myDATA so the issuer can correct it.

The rule is simple: whatever was issued is corrected with a new, transmitted document, not by deleting it in your software. That is why it pays to check the customer and amounts before you press “issue”.

eFluper connects directly to myDATA on every plan, including the free one. You link your account once with the access credentials you create at AADE, and from then on:

• every document is sent automatically on issue, or manually if you prefer, and comes back with its MARK, UID and QR code,
• you receive your myDATA data as issuer and as recipient, so you also see the documents others issued to you,
• you can create purchase documents from myDATA data, without retyping.

When you need e-invoicing (B2B, B2G, or retail without a cash register), you switch on the connection to the certified provider Impact, from €95 a year (excl. VAT), without changing software.