December. The last guests left in October, every key hangs on its hook and reception is quiet. But in March the phone will ring. Your accountant will ask about a July receipt that "is not in myDATA", or an August cancellation that was never closed.
A mistake you find in December is fixed calmly. The same mistake in March means digging through emails, reservations and the extranet. Below are six checks a hotel or a rooms-to-let property can do in one afternoon, before the year closes.
If you issue from Bookmatrix.com, most of this is in one list, because every document is sent to myDATA the moment you issue it (see how on the myDATA E-Invoicing page). The checks apply to any software, though.
Check 1: Every document has a MARK
When myDATA accepts a document, it gives it a MARK, the unique registration number. A document without a MARK never reached AADE: it was rejected, it was not sent, or AADE did not answer at that moment.
- Filter the year's documents and keep the ones without a MARK.
- For each one, read the error message. It usually says what is wrong: a wrong VAT number, a wrong date, totals that do not match.
- Fix it and send it again. If you are not sure about the numbering, ask your accountant before you resend.
In Bookmatrix.com every document shows its myDATA status next to it, so the unsent ones stand out at a glance.
Check 2: Every stay has its climate fee document
The climate crisis resilience fee is charged per day of use and per room or apartment. For every stay a special document, the fee collection receipt, is issued. In myDATA it is document type 8.2. Check that every stay of the year has its own.
Two points are easy to miss:
- Stays that cross into a month with a different amount. According to AADE's FAQ, when a stay spans months with different fee amounts, the special document is issued for each month separately, not at departure. A stay from 29 October to 3 November needs two.
- Free stays. They are not charged the fee. They still count in the total days of use on the declaration, as free ones.
In Bookmatrix.com the fee is calculated per stay and issued as its own document, next to the receipt. For the amounts and the declaration, see also our article on the climate resilience fee.
Check 3: A fee declaration for every month
The fee is paid over with monthly declarations on myAADE. Each declaration is due by the last day of the month after the month in which the special documents were issued. So the December 2026 declaration is due by 31 January 2027.
- Go through the months one by one. Every month with stays needs a submitted declaration.
- For a month with no stays and no special documents, there is no obligation to file a zero declaration.
- If a declaration is missing, myAADE accepts late initial declarations too, for periods from 01/01/2024 onwards.
- If you find a mistake in a declaration you already finalised, it cannot be corrected on myAADE. You file a request in the "My Requests" application, with supporting documents.
Check 4: Every cancellation was closed properly
A document with a MARK cannot be deleted. If a reservation was cancelled after a receipt or invoice was issued, there must be either a cancellation of the document in myDATA or a credit note. For retail receipts the credit note is type 11.4. For invoices it is type 5.1, which carries the MARK of the original.
- Pull the list of the year's cancelled reservations.
- For those that had a document, check that the document is cancelled or credited.
- Which of the two routes fits each case, especially when you kept a cancellation fee, is your accountant's decision.
Note: documents issued through an e-invoicing provider (ΥΠΑΗΕΣ) cannot be cancelled in myDATA. AADE's own technical documentation has an error code for it. There, the only route is a credit note.
Check 5: Invoices to businesses and mandatory e-invoicing
Under decision A.1128/2025, invoices to businesses in Greece (B2B), to businesses outside the EU (non-retail) and to the public sector are issued only electronically, through a certified e-invoicing provider (ΥΠΑΗΕΣ) or AADE's free timologio app. Receipts to private guests are outside this scope.
For businesses in the second period, meaning those not in the first (gross income above €1,000,000 on the 2023 tax return), decision A.1197/2026 (Gazette B 5905/30.09.2026) set the start at 2 November 2026. From 2 November 2026 to 31 January 2027, a gradual roll-out with parallel use of the old methods is allowed, under conditions.
- Check with your accountant which channel you declared to AADE: an e-invoicing provider or timologio.
- Make sure invoices to companies and travel agencies after 2 November went through that channel.
- Close anything pending before the transition period ends on 31 January.
In Bookmatrix.com, invoices to businesses go through an e-invoicing provider with the myDATA E-Invoicing add-on (€90 a year plus €150 one-time for the provider setup). Receipts to myDATA are included in every plan.
Check 6: Short-term stay declarations, if you have an AMA
If any of your properties are in the Short-Term Rental Registry, every stay is declared separately. The "Short-Term Stay Declaration" is due by the 20th of the month after the guest's departure. For December departures, that means by 20 January.
- If a rental was cancelled and the guest paid under the cancellation policy, an initial declaration is due by the 20th of the month after the cancellation.
- Amendments are possible until 28 February of the year in which income tax returns are filed. For 2026 stays, that is 28 February 2027.
The Bookmatrix.com Short-term Rental Registry keeps the list of what is due per month and sends a reminder seven days before the deadline.
The list on one page
- No document of the year without a MARK.
- Every stay has a fee document, and a separate one per month where the amount changed.
- A fee declaration for every month with stays. December by 31/1.
- Every cancelled reservation with a document has a cancellation or a credit note.
- Invoices to businesses after 2/11 through the channel you declared. Transition until 31/1/2027.
- Short-term stay declarations by the 20th of the next month. Corrections until 28/2.
With 200 documents a year, the check takes a few hours. With 2,000, the difference is whether you see them in one list with a status, or look them up one by one. To see how a receipt reaches myDATA in three taps, read this article.
Frequently asked questions
A document was rejected in August. Do I send it now?
First fix the reason for the rejection. Before you resend it with an old date, talk to your accountant about how the delay will be handled.
Do I need an e-invoicing provider if I only issue receipts to private guests?
The mandatory e-invoicing of A.1128/2025 covers invoices to businesses and the public sector. If you issue even a few invoices to companies or travel agencies, it applies to you.
Do I file a fee declaration for the winter months when I am closed?
No. If you had no stays and issued no special documents, there is no obligation to file a zero declaration.
Sources
- AADE: FAQ on the climate resilience fee declaration (January 2026, in Greek)
- AADE: Decision A.1128/2025 on mandatory e-invoicing (Gazette B 4937/16.09.2025, in Greek)
- AADE: Decision A.1197/2026, new timetable for the second period (in Greek)
- Text of A.1197/2026 (Gazette B 5905/30.09.2026, Taxheaven, in Greek)
- AADE: Short-term rental of property (declaration deadlines, in Greek)
- AADE: myDATA REST API documentation v1.0.12 (document types, error codes, 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 to close next year without digging? 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.