Two things get confused constantly. myDATA is the mandatory transmission of your accounting documents to the Greek tax authority (AADE). E-invoicing is issuing the document itself in a structured electronic format, through a certified provider.
The first already applies to everyone. The second is becoming mandatory — and preparing for it takes longer than most people assume.
Not sure where you stand today?
Tell us which software you use and we will tell you what is missing to be ready.
What each one is
| myDATA | E-invoicing | |
|---|---|---|
| What it does | Transmits document data | Issues the document electronically |
| Where it ends up | In AADE’s digital ledgers | With your customer and AADE |
| Who does it | Your software or your accountant | A certified provider |
| Status | Already in force | Progressively mandatory |
In practice: you can do myDATA without e-invoicing. The reverse does not hold — e-invoicing includes transmission.
Who it applies to
The direction is clear: every business issuing accounting documents. What differs is when, and in what order.
- Transactions with the public sector (B2G): e-invoicing already applies here.
- Business-to-business (B2B): phased into the obligation.
- Retail to consumers: covered by receipt transmission.
Important: dates and scope have shifted several times. Before you commit to anything, confirm the timeline that applies to your specific case with your accountant and with AADE’s official guidance.
The four transmission routes
Four paths, with different costs and different suitability.
| Route | Suits | Cost |
|---|---|---|
| Certified e-invoicing provider | Businesses with volume or B2B trade | Per document or package subscription |
| Commercial/accounting software with a connection | Most SMEs | Included, or a small uplift |
| AADE’s timologio web form | Very low volume | No cost |
| Cash register / POS | Retail | Upgrade cost |
The second covers most cases. If your software already supports it, the job is configuration rather than a new purchase — the same reasoning applies as in custom software vs off-the-shelf.
What changes day to day
Less than you fear, if your software is right. Rather more, if you are still writing invoices by hand.
The four real changes:
- Every document receives a unique registration number from AADE. Without it, the document counts as untransmitted.
- Corrections happen through cancellation or credit notes, not deletion.
- Transmission has a deadline. You cannot let the month close and then send everything at once.
- Your expenses must reconcile with what your suppliers transmitted. Discrepancies get flagged.
The fourth is what creates most of the work in year one.
What it costs
| Component | Indicative range |
|---|---|
| Certified e-invoicing provider | €10 – €60 per month, by volume |
| Commercial software upgrade | €0 – €500 one-off |
| ERP-to-provider connection | €500 – €3,000 |
| Configuration and training | €200 – €800 |
These figures are indicative and vary considerably by provider and document volume. Ask for a quote based on your actual monthly invoice count, not on a packaged tier.
If you run an e-shop, the connection carries extra requirements — covered in detail in our guide to connecting an e-shop to myDATA.
Want an estimate for your case?
Send us your monthly document count and we will propose the cheapest compliant option.
The benefits nobody advertises
An obligation is an obligation. But there are genuine returns:
- Less manual data entry in bookkeeping.
- Faster payment, because the invoice arrives immediately and does not get lost.
- Fewer errors in VAT numbers, amounts and rates.
- A clear cash-flow picture in near real time.
- Simpler audits, because the data is already there.
A business that treats this as an opportunity to tidy up comes out ahead. One that treats it as a chore pays the same money without the benefit.
Five steps to get ready
- Document how you currently issue each type of document. There are often two or three parallel methods in use.
- Ask your software provider what is already supported and what it will cost.
- Agree the division of roles with your accountant: who transmits what.
- Test in a sandbox environment before the applicable date.
- Train everyone who issues documents. Most errors are human, not technical.
Step three solves half the problems. Plenty of businesses discover something was never transmitted because both sides assumed the other was handling it.
Frequently asked questions
Do I definitely need a provider?
Not in every case. If your commercial software transmits correctly and you are not yet under an e-invoicing obligation, that is enough.
What happens if I transmit late?
Penalties apply and discrepancies appear in your ledgers. Ask your accountant about the current penalty framework.
Can I carry on with paper invoice books?
Only in limited exceptions, and with an obligation to transmit afterwards. It is not a sustainable position.
Does my ERP connect?
Most Greek ERPs offer a ready connection. See what an ERP does, and ask your provider for written confirmation.
Does anything change for my e-shop obligations?
Invoicing duties sit on top of the ones already in force — see the full picture in legal requirements for a Greek e-shop.
The first step
Open the software you use and find an invoice from last month. Check whether it carries a registration number from AADE.
If it does not, start there. It is the fastest diagnosis of where you actually stand.
Next step
Book a free 30-minute call with the team at The Dev Alley. We will review your invoicing flow and tell you what needs to change.