Greece's myDATA Deadline and the Dock: What Changes for Berth Invoices Before 1 October 2026

From 1 October 2026, the Greek businesses outside the first phase must issue business-to-business invoices electronically and transmit them to AADE through myDATA, with an adjustment period running to 31 December 2026. For a resort or hotel with moorings, the practical question is narrower than the headlines suggest: some of what your dock bills is business-to-business and therefore in scope, and if those charges live in a spreadsheet that someone re-keys into accounting each month, that process will not survive a real-time clearance model. This is what changes, which berth invoices are affected, and what to fix before the deadline.

Key Takeaways

• Greece's second e-invoicing phase starts on 1 October 2026, with an adjustment period to 31 December 2026.

• myDATA reporting has been mandatory since 2021; what changes now is structured e-invoicing under a clearance model.

• Domestic business-to-business invoices are in scope, as are invoices to non-EU businesses; intra-EU is optional and consumer invoicing is not covered by the structured requirement.

• At the dock, charter operators, yacht management companies, brokers and corporate accounts are the business-to-business exposure.

• Guest moorings billed to an individual's folio are consumer transactions, though myDATA reporting still applies.

• Monthly re-keying of berth charges into accounting is the process most likely to break.

• Compliance runs through a certified provider, AADE's free Timologio tool or direct integration, so the question for the dock is how its invoice data reaches that channel.

• Confirm your own phase, scope and penalty exposure with a Greek tax adviser rather than relying on a summary.

What myDATA already required, and what is actually new

myDATA is the digital platform operated by AADE, Greece's Independent Authority for Public Revenue, and Greek businesses have been transmitting invoice and accounting data to it in near real time since 2021. Each transaction is validated and given a unique registration number, commonly called the MARK, along with a QR code used on the document. If your property operates in Greece, your finance team already lives with this.

What changes in 2026 is the move from reporting data about invoices to issuing structured electronic invoices under a clearance model, where myDATA validates the invoice before it reaches the customer. The legal basis sits in Law 5222/2025 and a series of AADE ministerial decisions, and the rollout is phased by business size.

The two phases, and which one your property sits in

The first phase covers businesses with gross revenues above €1 million in the 2023 tax year and began on 2 March 2026, after a postponement from an earlier February date, with a gradual implementation window to 3 May 2026. Most resort and hotel operating companies of any scale fall into this group, so if that describes your entity, the obligation has already begun.

The second phase covers the remaining businesses established in Greece and begins on 1 October 2026, with an adjustment period to 31 December 2026. This is where smaller operating entities land, and it matters for properties that run the marine amenity through a separate company, a concession holder or a local subsidiary, because that entity may sit in phase two even when the group does not. Check which legal entity issues your berth invoices before you assume which deadline applies.

Which of your dock's invoices are actually in scope

Scope is where most of the confusion at property level comes from. Domestic business-to-business transactions are mandatory, invoices to businesses outside the EU are mandatory, intra-EU business-to-business remains optional for now, and structured e-invoicing is not required for consumer transactions. The obligation attaches to businesses established in Greece that transact with other domestic businesses, which matters for chain-owned properties, because an entity that is only registered for Greek VAT without being established there may sit outside the mandate. That distinction is worth confirming with your adviser rather than assumed either way.

Applied to a dock, that produces a clear split. Charges to charter operators, yacht management companies, brokers, agencies and corporate accounts are business-to-business and in scope. A mooring billed to an individual guest's folio is a consumer transaction, so the structured e-invoice requirement does not bite, although myDATA reporting still applies to the revenue. Most resort docks carry both, which is exactly why the dock cannot be left out of the project.

Why a spreadsheet-run dock is the weak point in a clearance model

Real-time clearance is unforgiving about timing and about data quality. An invoice has to be issued in a structured format, validated, and carry its registration reference, which means the underlying charge data has to be complete and correct at the moment of issue rather than tidied up at month end. A dock that records berth nights, shore power and services on a spreadsheet, then hands a summary to accounting weeks later, cannot reliably meet that.

The failure modes are predictable. Charges get invoiced late because nobody logged them, a corrected berth charge produces a document that no longer matches what was cleared, and the audit trail between the dock's own records and the cleared invoice depends on one person's memory. None of this is a software problem in the abstract, and all of it becomes a compliance problem once the invoice has to be cleared as it is issued.

Three routes to compliance, and why the dock sits upstream of all of them

Businesses have three routes reported in public guidance: use an AADE-certified e-invoicing provider, use Timologio, the free tool AADE provides for creating and transmitting compliant invoices, or integrate a business system directly with the myDATA interface. Larger properties generally take the certified-provider route, because it handles validation, formats and archiving centrally.

Whichever route your property takes, the dock is upstream of it. Your dock system does not have to talk to AADE itself; what it does have to do is hand complete, structured, timely charge data to whatever certified channel the property already uses, with a clean reference back to the berth record for audit. That is an operational requirement, and it is answerable today.

What to fix at the dock before the deadline

Work through these in order, because each one depends on the last:

1. Identify which entity issues berth invoices and confirm its phase and deadline with your tax adviser.

2. Split your dock revenue by counterparty type, separating business accounts from guest folios, so you know what falls under the structured requirement.

3. Move berth, mooring, power and service charges onto a system that records them as they happen, so the charge data is complete at the moment of invoicing rather than reconstructed later.

4. Agree the handover between the dock and finance: what data goes to the certified channel, in what format, and how often.

5. Define how corrections work, since credit notes and amended charges have to stay consistent with what was already cleared.

6. Test before the transition period ends, using real business accounts rather than a sample, while the graduated enforcement window still gives you room.

What to ask the vendor running your dock

Put these questions to any platform that produces your berth charges, including your current spreadsheet-and-accounting arrangement:

• Can it produce structured invoice data per transaction, with the fields our certified provider requires?

• Can charges be invoiced at the point they occur rather than in a monthly batch?

• How are credit notes and corrections handled, and do they stay linked to the original charge?

• Can we trace a cleared invoice back to the berth, vessel and dates it came from?

• Can business accounts be flagged separately from guest folios, so the two invoicing routes stay distinct?

• What has the vendor already done for other Greek properties, and can we speak to one?

Harba runs the dock as one operational record covering berths, moorings, guest and vessel records, payments and invoicing, which is the foundation this exercise needs, and the specifics of how dock invoice data reaches a Greek certified channel are worth walking through on a call for your property.

Treat the deadline as a reason to fix the dock's records

The useful way to read this is that a regulatory date has put a deadline on something a property should want anyway: charges captured as they happen, invoices that match the operational record, and a dock whose numbers finance can reconcile. Properties that already run the marine amenity on one system are mostly doing integration work; properties running it on a spreadsheet are doing the underlying operational work first, which takes longer. The wider sequence for that is set out in the guide to moving a resort dock off Excel in 90 days.

To work through what your dock would need to hand to your certified channel, book a demo and bring your berth charge types and your invoicing setup to the call.

This article is general information about a changing regulatory timetable, not tax advice. Confirm your phase, scope and obligations with a Greek tax adviser or your certified e-invoicing provider.

Frequently Asked Questions

1. What is the myDATA deadline on 1 October 2026?

It is the start of the second phase of Greece's mandatory business-to-business e-invoicing programme, covering the businesses not captured by the first phase, with an adjustment period to 31 December 2026. From that point those businesses issue structured electronic invoices that are transmitted to AADE through myDATA and validated before delivery. A separate 12 October 2026 date applies to e-Transportation reporting, so do not confuse the two. Confirm which phase your own entity falls into with a Greek tax adviser.

2. Do mooring charges billed to a hotel guest need an e-invoice?

Structured e-invoicing under this mandate applies to business-to-business transactions rather than consumer ones, so a mooring billed to an individual guest's folio is not covered by that requirement. myDATA reporting still applies to the revenue, so the charge cannot simply sit outside your records. Where the counterparty is a company, such as a charter operator or a yacht management business, the structured requirement does apply.

3. Which berth invoices are in scope for a resort dock?

Invoices to Greek businesses are in scope, as are invoices to businesses outside the EU, where the issuing entity is established in Greece. At a dock that typically means charter operators, yacht management companies, brokers, agents and corporate accounts. Invoices to businesses in other EU member states remain optional for now under the Greek rules. Split your dock revenue by counterparty type before assuming which route each invoice takes.

4. What happens if a berth invoice is not issued correctly?

Under the penalty regime reported for the mandate, non-compliance on a VATable transaction can attract an administrative fine equal to 50 percent of the VAT associated with that transaction, while non-VAT transactions carry a fixed penalty of €500 or €1,000 depending on the accounting system the taxpayer maintains. Exposure accumulates across invoices, so volume matters. Treat these as indicative and confirm your own exposure with a Greek tax adviser, since penalty details have been revised alongside the timetable.

5. Does our dock system need to connect to AADE directly?

Not necessarily. Compliance is generally handled through an AADE-certified e-invoicing provider, through AADE's free Timologio tool, or by integrating a business system directly with the myDATA interface. The dock sits upstream of whichever route you choose, so the requirement on the dock is to produce complete, structured, timely charge data with a clear audit trail back to the berth record.

6. We run the marina through a separate company. Which deadline applies?

The obligation follows the entity that issues the invoice, so a concession holder, subsidiary or separate operating company can sit in a different phase from the group that owns the hotel. Identify which entity issues berth invoices, then confirm its phase against its own revenue with your tax adviser before planning the work.