Connecting Shopify to myDATA: how to issue invoices and receipts
What AADE, the Greek tax authority, asks of an online store, what is changing in how documents are issued, and the ways to connect that exist in practice. Everything you need to know as an e-shop owner.
If you run a Greek Shopify store, the question is not whether you will connect to myDATA but how. Transmitting documents to myDATA has been mandatory since 2021, and Greece is now making the digital way of issuing them mandatory as well. This guide explains what has to be issued, when, and the options you have for doing it without typing orders in by hand.
How do I issue myDATA invoices from Shopify? The short answer
With an app that issues the document and transmits it from inside Shopify itself, with no second program and nothing typed in by hand.
You install Timologio from the Shopify App Store, fill in your business details and connect your account with the certified e-invoicing provider. Setup happens once and takes about half an hour. From then on, your customer types their AFM, the Greek tax number, in the cart, their details arrive from AADE, and the invoice issues on its own with MARK and QR from myDATA and reaches the customer by email. Orders without an AFM get a retail receipt, if you switch that on, and the transport details go on the same document.
The setup steps, one by one, are on the Setup page. The rest of this guide explains what the law asks of an e-shop, what is changing and where the usual mistakes happen, so that you know what you are switching on and why.
What myDATA asks of an online store
Two things, and they often get mixed up: issuing the document and transmitting it.
Issuing
Every sale needs a document. An invoice when the customer is a business and gives an AFM, a retail receipt when they are a consumer. The document must carry the details the law requires, the right VAT and a number from a declared numbering series.
Transmitting
The document must also reach myDATA. There it gets a MARK, the unique registration number that proves it was transmitted. A document without a MARK has not finished its journey, even if the customer already has it in hand.
What is changing in how documents are issued
Greece is moving every business to digital invoicing through myDATA. The dates, and who they apply to, are on our page about the e-invoicing declaration (in Greek).
What becomes mandatory is the digital way of issuing. No particular method is imposed, and no particular supplier. Our app supports every kind of e-shop running on Shopify.
The ways to connect Shopify to myDATA
Four routes, all accepted by AADE. They differ in how much work is left to you and in where the issuing happens.
| Route | How it works | What is left to you |
|---|---|---|
| AADE's own app | You enter every document yourself in the app AADE provides. | All the data entry, one order at a time. It does not connect to Shopify. |
| Accounting software or an ERP | The program issues and transmits. Some accept orders imported from a file or through a bridge. | Importing the orders and maintaining the bridge. Usually a software subscription too. |
| A certified provider, from inside Shopify What Timologio does | The customer types their AFM in the cart and it is validated on the spot, with the details arriving from AADE. Timologio prepares the document and sends it to be issued, and the provider transmits it to myDATA and returns the MARK and QR. Invoices, retail receipts and transport details all come out of the same app. | Half an hour of setup, once. Then nothing to do on any order. See the steps |
| Self-provider | The business gets certified as a provider itself and issues on its own infrastructure. | The certification, the audits and the upkeep. It makes sense for large organizations. |
Invoice, receipt and delivery note: what is the difference
Three different obligations, often confused because in an e-shop they all happen on the same order.
Invoice
Issued when the buyer is a business and gives an AFM. It needs the customer's company name, registered address, business activity and AFM, all correct. That is why validating the AFM right in the cart matters: one wrong digit means wrong details on an official document, and the only fix is a credit note.
Retail receipt
Issued when the buyer is a consumer, which covers the great majority of an e-shop's orders. It needs no customer details, but it does need its own numbering series and its own transmission.
Delivery note
It travels with the goods. It used to be a separate form. Today the transport details can be added to the invoice or receipt already being issued, and Timologio adds them there. One document, one MARK, one numbering series fewer to agree on.
What changes for your customer
The customer's experience gets better, because they can now ask for an invoice right there, something that was not possible on Shopify until now. For e-shops, that means more carts and more sales.
With Timologio, a field appears in the cart for customers who want an invoice. Anyone who doesn't need one leaves it alone, and the order goes through as before. For the great majority of orders, the ones from consumers, nothing changes in the way they buy.
Whoever asks for an invoice types their AFM, and that is where the difference lies. The AFM is validated on the spot, and the Timologio app fills in the company name, registered address and tax office with details straight from AADE. The customer doesn't type details they might get wrong, and you don't receive an invoice request with half the details, or the wrong ones. In systems that collect the AFM as a plain comment on the order, this check does not exist, and the mistake shows up later, on a document already issued.
Once issued, the document can go to the customer by email, with the PDF attached. The sender shown is your store's name.
Γεια σας,
Σας στέλνουμε συνημμένο το παραστατικό ΤΔΑ 000123 για την αγορά σας από Κατάστημα Δείγμα.
Το παραστατικό έχει διαβιβαστεί ηλεκτρονικά στο myDATA της ΑΑΔΕ, οπότε θα το βρείτε και στα βιβλία σας.
Η έκδοση έγινε αυτόματα από το Timologio, την εφαρμογή που εκδίδει παραστατικά myDATA μέσα από το Shopify: timologio.app
Here the provider adds its own line and its logo.
What changes when you ship by courier
This is the point almost no Greek e-shop sees coming.
Retail sales are exempt from the delivery note obligation when the shipment travels with a sales document. The exemption does not apply, however, to parcels handed to a courier or a logistics company when the receipt is not visible on the parcel and the carrier cannot show it.
In practice this covers almost every online store, because almost none of them stick the receipt on the outside of the parcel. If you ship by courier, the obligation applies to you, and that is why transport details are not a luxury but part of compliance. Ask your accountant about your own case.
What happens when Shopify sends no VAT
It happens more often than you would think, and it is where a document comes out wrong without anyone noticing.
Shopify calculates and sends a VAT breakdown only if the store's tax settings have been set up. Many Greek stores have never set them up, because until now they had no need to, so their orders arrive without VAT. A document issued that way comes out with zero VAT. It is official, it has a MARK, and it is wrong.
In Timologio the fix is to declare the rate you charge, so that it is used whenever an order doesn't bring its own. One point needs care: this works when all your products carry the same rate. If you sell products at different rates, one declared rate is not enough, and Shopify's tax settings have to be set up properly.
Sales to consumers in other EU countries are a separate case. If your business is registered in the EU OSS scheme, the receipt goes out at 0% Greek VAT with the customer's country VAT on a separate line, and the rate comes from Shopify's tax settings, not from your declared rate. See how the OSS receipt is issued from Shopify.
What happens with refunds and cancellations
An official document cannot be cancelled once it is issued. That is not a limit of the app. It is how myDATA works.
The correction is made with a credit note, a second document that reverses the first. The original stays in myDATA and the credit note sits beside it. That is why the moment that needs care is before issuing, not after, and why it is worth looking at a test order first.
In Timologio, when an order is refunded in full, the credit note issues automatically. On a partial refund, the app prepares the credit note with the lines and quantities refunded in Shopify, and you check them and issue it with one click, from the list or from the order itself. You can also issue a credit note whenever you need one, for the whole document or for as many units as you choose, with the reason you write yourself. In every case the credit note uses one document from your package, like any other issue.
What e-invoicing costs an e-shop
Two charges, and it matters to keep them apart, because they are paid to different parties.
The app subscription
Paid through Shopify. Timologio starts at $6.99 a month, and no plan sets a cap from us. Shopify charges in US dollars.
The provider's package
Paid directly to the provider, per AFM, and yearly. This is the package your documents come from. They count per year, not per month, so a December with three times the orders doesn't force you to change package in the middle of the month. You see which packages exist and what each one costs inside the app.
When you compare solutions, check whether the price you see includes the document package, and whether there is a monthly cap. Those are the two points where the final cost differs most from what the starting price suggests. For comparison: the provider package we recommend counts your documents over twelve months, not month by month. Full details on the pricing page.
Five mistakes Greek e-shops often make
All of them can be fixed, but four of the five only with a credit note.
Treating the order PDF as a document
The confirmation email Shopify sends is not a tax document, however official it looks. It has no MARK, no numbering series, and AADE never sees it.
Issuing the same sale from two systems
If your accounting office already issues the retail receipts and you switch retail receipts on here too, the same sale is declared twice in myDATA. Agree first on what is issued from where, and turn on only those switches.
Issuing with zero VAT without knowing it
The subject of the VAT section above. A document with the wrong VAT is just as official as a correct one, and just as hard to take back afterwards.
Using one numbering series for everything
Invoices, credit notes and retail receipts need separate series, each with its own starting number. It is the one point your accountant has to answer before you switch issuing on.
Ignoring delivery notes because they sell retail
The retail exemption does not cover parcels that leave by courier when the receipt is not visible on the parcel. That applies to almost every e-shop, and it is the mistake usually discovered in a tax audit.
Questions about connecting to myDATA
How do I issue myDATA invoices from Shopify?
With an app that issues the document and transmits it from inside Shopify itself. With Timologio you install the app from the Shopify App Store and connect your account with the provider once, about half an hour in all. From then on, every order with an AFM issues its own invoice with MARK and QR. Orders without an AFM get a retail receipt, if you switch that on.
What is a MARK?
It is the unique registration number myDATA gives every document as soon as it receives it. Without a MARK, a document does not count as transmitted. On documents issued through a provider, the MARK and a QR code are printed on the document, so that it can be checked.
What happens to orders placed before I connected?
They are not issued retroactively. Issuing starts the moment you turn on the matching switch and covers the orders that come in from then on. For earlier orders, agree with your accountant on what has been declared and how.
Can I issue only invoices here and keep retail receipts elsewhere?
Yes, and it is common. Each document type has its own switch, and they all start switched off. If you already issue retail receipts from a cash register or through your accounting office, don't switch the same type on here as well, because the same sale would be declared twice in myDATA.
What is a certified e-invoicing provider?
It is a company licensed by AADE to issue and transmit documents on behalf of businesses. The license requires ISO/IEC 27001 certification and keeping the data on infrastructure inside the European Union. The account opens in your business's name and AFM, which is why you remain the legal issuer. Timologio issues through Wrapp, licensed by AADE under code 029.
Do I need separate numbering series?
Yes. Each document type has its own series and its own starting number, so invoices, credit notes and retail receipts each need a separate one. This is the one point where you need your accountant, and the setup guide inside the app shows you what to ask them.
More questions are answered on the homepage, and the setup steps are in the setup guide.
See it in your own store
Half an hour of setup, once. AFM collection and validation work from day one, and issuing switches on when you decide.
Have a question? Write to us
We reply in Greek or English, whichever you prefer. You don't need the app installed to ask.
If you like, we set it up with you. You give us collaborator access to your store, and we add the block to your cart page and match it to your theme, at no charge.