E-invoicing and your e-shop: what changes and what doesn’t.

From 2 November 2026, e-invoicing is mandatory for smaller businesses too, and therefore for every e-shop that issues even a few invoices to businesses. For an online store, the change doesn’t stay in the accounts department: it affects the checkout, the order emails and the connection between WooCommerce and your provider or ERP.

Below you’ll find what applies today, with the new dates announced on 30 September, what doesn’t change for retail sales, and a checklist for WooCommerce. This isn’t tax advice. Every business has its own particularities, so confirm the steps with your accountant.

01E-invoicing: who and from when

The obligation covers invoices to businesses in Greece (B2B), to businesses in non-EU countries and to the public sector (B2G). It applies in two periods, based on the gross revenue declared for tax year 2023.

Most small e-shops fall into the second period. The original date was 1 October 2026, but joint decision A.1197/2026 moved it to 2 November, as the Ministry of National Economy and Finance and AADE announced on 30 September 2026. Many texts online still give the old date.

Until 31 January 2027 you can also keep issuing in parallel the way you already do, i.e. with commercial software, an ERP or the special form, provided you submitted the relevant declaration in time. From 1 February 2027, these invoices are issued and transmitted to myDATA only through an e-invoicing provider or the timologio and myDATAapp applications. Transmission from an ERP will no longer be accepted for these documents.

According to AADE, about 655,000 second-period businesses, almost 70%, were already using a provider or its apps at the end of September. For those who fall behind, the consequences aren’t theoretical. As AADE has clarified, if an e-invoice isn’t issued where one is required, the invoice is considered not to have been issued. The fine is 50% of the corresponding VAT or, for transactions without VAT, €500 or €1,000 per audit, depending on the books you keep.

02A provider or the free timologio app?

AADE leaves two routes. The first is an E-Invoicing Provider: a private company whose software has received a certificate of suitability. AADE publishes the list of licensed software, which also shows which ones cover public contracts or also work as a cash register system and POS. Providers usually charge a subscription, which varies with volume and services.

The second is AADE’s free apps: timologio for desktop and myDATAapp for mobile, which also cover invoices to the public sector. If from 2 November 2026 you issue only through them and don’t want the phase-in period, you don’t need a “Declaration of Start of Electronic Issuance of Documents”. If you use a provider, the declaration is required, with a start date of 2 November 2026.

For an e-shop, the choice comes down to volume. In timologio you enter each invoice separately, so it suits a store that issues few invoices a month. If there are dozens, or if you want them issued automatically with the order, you need a provider with a ready-made connection (plugin or API) for WooCommerce, or an ERP that works with a provider.

03myDATA, classifications and MARK in plain language

myDATA is AADE’s electronic books platform. It’s where the summary of every document you issue ends up, wholesale or retail, to businesses or individuals. When the customer is a business, their own books are updated automatically too. The data arrives from commercial software or an ERP, from the special form, from an electronic fiscal device (FIM) for retail, or from a provider.

With every successful transmission, AADE assigns a Unique Registration Number (MARK), the confirmation that the document has been registered. The classification is how the transaction is categorized, e.g. sale of goods or provision of services. For income it can be sent with the document or later; for expenses it’s always done afterwards.

This is exactly where you need your accountant. The e-shop must send the right document type, VAT category and classification for every product or service. These are set once and checked before automatic issuing starts, because a mistake in the setup is repeated in every order.

04Retail in your e-shop: what doesn’t change

Most of an e-shop’s orders come from individuals. For these, AADE is clear: mandatory e-invoicing brings no change to the obligations and the way retail documents are issued. The receipt is issued as it is today and its summary is transmitted to myDATA.

“As it is today” isn’t the same for everyone. In some e-shops the receipt comes from commercial software connected to an FIM, in others from a provider that also works as a cash register system. Which way suits your business is for your accountant to decide, not the plugin.

A point that often causes confusion: the mandatory connection of POS terminals to cash register systems applies to physical terminals. AADE decision A.1074/2024 states that distance sales (e-commerce and marketplaces) are not covered by it. If, however, you also have a physical store with a POS, the connection rules apply there, and it’s a good idea to go over them with your cash register technician.

05What a WooCommerce e-shop needs technically

WooCommerce doesn’t issue legal tax documents on its own. It needs a connection to a provider or ERP and a few changes to the checkout. These are the things we most often see missing:

• Receipt or invoice option at checkout. The customer chooses, and the business fields only appear when they ask for an invoice.
• Fields for VAT number (AFM), company name, business activity, address and tax office (DOY). Your accountant confirms which ones are mandatory for your documents. The checkout must save them as order fields, not in a free-text comment.
• VAT number check. A first format check catches typos. For full details, AADE offers the “Search for Basic Business Registry Details”service, a web service with special credentials, so the checkout can fill in the company name and address from the VAT number. For customers from other EU countries there’s VIES.
• Connection to a provider or ERP. When the order is completed or paid, the e-shop sends the data, gets back the MARK and the document’s PDF, and saves them in the order.
• PDF in the order email. The customer receives the document with the confirmation or the shipping notification, and can also find it in their account.
• Returns and cancellations. A refund in WooCommerce must lead to the corresponding credit document, not “delete” the original.
• A plan for when the provider doesn’t respond. The order mustn’t get lost: it needs automatic retries and a notification to the administrator.

If your e-shop already has a myDATA plugin, check whether it sends invoices through a provider or directly to myDATA, like an ERP. Direct transmission won’t be enough for B2B invoices after 31 January 2027.

The WooCommerce e-shops we build come with this connection set up, to the provider or ERP your accountant already uses, along with the checkout fields. If you’re also changing payment methods, see our guide to payments in WooCommerce.

06E-invoicing checklist for e-shops

1. Find out from your accountant which period you belong to and whether the start declaration has been submitted, where needed.
2. Decide whether you’ll work with a provider or with timologio, depending on how many B2B invoices you issue a month.
3. If you choose a provider, ask whether it has a ready-made connection for WooCommerce, who maintains it and what happens when a new version of WooCommerce comes out.
4. Agree with your accountant on document types, numbering series, VAT categories and classifications.
5. Add an invoice option, business fields and a VAT number check to the checkout.
6. Test every scenario on staging: receipt, invoice, cancellation, refund and connection failure.
7. Make sure the MARK and the PDF are saved in the order and go out with the email.
8. Stop issuing B2B invoices in parallel from an ERP or the special form before 1 February 2027.

07FAQ

I only sell to individuals. Does this affect me?

For retail receipts, AADE says nothing changes. But if you issue even one invoice to a business, it must be electronic.

Is it enough to send the invoice as a PDF?

No. The PDF is just the printout. An e-invoice is one issued through a provider or through timologio and myDATAapp and registered in myDATA. The PDF you send the customer simply has to match it.

My ERP already sends to myDATA. Am I covered?

For second-period B2B invoices, issuing and transmitting from an ERP is allowed in parallel only until 31 January 2027. After that you need a provider or AADE’s apps, so ask your ERP vendor whether it connects to a provider.

If you’re not sure what your e-shop does with tax documents today, the technical audit for e-shops checks the checkout, orders and emails. For a specific provider integration, contact us.