You have seven rooms in a village with a sea view. You know how to make beds, answer Booking.com messages and recommend the taverna that is worth it. But every time your accountant says "this has to show in myDATA", your stomach tightens.
This article is for you. Without accounting terms where they are not needed, it explains what myDATA is, what you send, when, and what your accountant does. By the end you will know what to ask.
What myDATA is, in two lines
myDATA is AADE's platform for electronic books. Every receipt or invoice you issue is sent there. When AADE accepts it, it gives it a number, the MARK (unique registration number). If a document has a MARK, AADE has it. If not, it does not.
With software connected to myDATA, this happens the moment you issue. See how Bookmatrix.com does it on the myDATA E-Invoicing page.
Rooms-to-let or short-term rental?
First, one distinction. The law separates:
- Furnished rooms and apartments to let: a tourist accommodation run as a business. It issues documents and sends them to myDATA. This article is about these.
- Properties in short-term rental (for example a flat on Airbnb): a private person can offer them without registering a business, for up to two properties. There, the main obligation is the declarations in the Short-Term Rental Registry. We wrote about that in our article on Law 5170/2025.
If you do not know which one you are, your accountant does. It is the first question to ask.
Which documents you issue
For a rooms-to-let property, daily life is four documents. The number in brackets is the myDATA type.
- Service Receipt (11.2), for a private guest. The law (Law 4308/2014, article 12) allows a retail document for sales to private consumers. You do not need the guest's tax number.
- Service Invoice (2.1), when a company or travel agency pays, with its VAT number.
- Climate resilience fee document (8.2), for every stay. It is separate from the receipt.
- Credit note (11.4 or 5.1), when a reservation is cancelled or something must be corrected after the document got a MARK.
How they reach myDATA
There are three routes:
- Software connected to myDATA. The connection needs myDATA REST API credentials (a user name and a key), which you get by registering on the myDATA platform with your TaxisNet login. From then on, each document is sent as soon as it is issued.
- AADE's free apps, such as timologio. You type each document there.
- A certified e-invoicing provider (ΥΠΑΗΕΣ in Greek).
For invoices to businesses there is a new rule. Under decision A.1128/2025, they are issued only electronically, through a certified provider or timologio. For smaller businesses (those without gross income above €1,000,000 on the 2023 tax return), decision A.1197/2026 moved the start to 2 November 2026, with a transition period until 31 January 2027. Receipts to private guests are outside this rule.
The climate resilience fee for rooms-to-let
Furnished rooms to let are among the accommodation types that pay the climate crisis resilience fee. It is charged per day of use and per room or apartment. Under article 44 of Law 5177/2025, for furnished rooms to let it is:
- €2 per room per night, from April to October.
- €0.50 per room per night, from November to March.
Example: a family books two rooms for 5 nights in August. 2 rooms × 5 nights × €2 = €20. You issue the special fee document for the stay, and the month's special documents are declared together on myAADE by the last day of the following month. For a month with no stays you do not file a zero declaration. Free stays are not charged the fee.
What you do and what your accountant does
You: issue the right document at the right moment, with the right customer details. Check that it got a MARK. Handle the cancellation or credit note when a reservation is cancelled.
Your accountant: classifies income and expenses in myDATA, files the VAT return (monthly or quarterly depending on your books, by the last working day of the following month) and the income tax return. Often they also file the fee declaration, if you have authorised them on myAADE.
The cleaner your side is, the fewer phone calls in March.
How Bookmatrix.com does it
- We connect your property to myDATA once, with you, using your own credentials.
- At check-out you open the reservation, choose receipt or invoice, confirm the charges and issue.
- The document is sent to myDATA, gets its MARK and is emailed to the guest as a PDF with a QR code.
- The climate fee is calculated per stay and issued as its own document.
Receipts to myDATA are included in every plan. For invoices to businesses through an e-invoicing provider there is the myDATA E-Invoicing add-on (€90 a year plus €150 one-time for the setup). For the three taps of a receipt, see this article.
Frequently asked questions
What is the MARK?
The unique registration number myDATA gives every document it accepts. It is the proof that the document reached AADE.
Do I need an e-invoicing provider if I only issue receipts?
Mandatory e-invoicing covers invoices to businesses and the public sector. If you only issue receipts to private guests, no. With your first invoice to a company or travel agency, yes.
The guest booked through Booking.com. Do I issue a receipt?
Yes. Your customer is the guest, not the platform. If they are a private person, they get a service receipt.
If I had no stays in a month, do I file a fee declaration?
No. There is no obligation to file a zero declaration for a month with no stays and no special documents.
I issued a wrong receipt. Can I delete it?
No. If it has a MARK, it is cancelled in myDATA or reversed with a retail credit note (11.4). Which of the two, your accountant will tell you.
Sources
- AADE: myDATA REST API documentation v1.0.12 (document types, error codes, in Greek)
- Law 4308/2014 (Greek Accounting Standards), article 12: retail documents (Taxheaven, in Greek)
- AADE: FAQ on the climate resilience fee declaration (January 2026, in Greek)
- Law 5177/2025, article 44: climate resilience fee amounts (Taxheaven, in Greek)
- AADE: Decision A.1128/2025 on mandatory e-invoicing (Gazette B 4937/16.09.2025, in Greek)
- Text of A.1197/2026 (Gazette B 5905/30.09.2026, Taxheaven, in Greek)
- AADE: Mandatory e-invoicing and digital delivery notes (in Greek)
- Mitos (gov.gr): VAT return, deadline and monthly or quarterly period (in Greek)
Updated: 14/10/2026. This article is general information, not tax or accounting advice. Your accountant has the final word on your own case.
Want myDATA to happen on its own from the reservation? Try Bookmatrix.com with a free 14-day demo, or leave your phone number at bookmatrix.com/form and we will call you on the next working day. Or call us at +30 2351 151525.