Greek e-invoicing reaches every business on 1 October. What that means if you run a small one

Everything written about Greek e-invoicing so far has been written for finance departments. Search it and you get compliance vendors explaining ERP integration to people with a CFO. That was fine while the rule only applied to large companies. It stops being fine on 1 October 2026, when the mandate reaches every business established in Greece, including the ones with no finance department, no ERP and no idea this is coming.

So here is the version for a business with one till.

This is not tax advice. I build websites. Everything below is what is publicly documented about the rule, written plainly. The person who should actually act on it is your accountant, and there is a specific thing to ask them at the end.

What the rule is

Greece already ran myDATA, the tax authority’s platform that your accounting software transmits invoice data to. That part is not new.

What is new, under Law 5222/2025, is that issuing invoices between businesses moves to a structured electronic format rather than paper or a PDF you email. It arrived in phases:

2 March 2026 — businesses with more than €1 million in revenue in the 2023 financial year.
1 October 2026 — everyone else established in Greece.

It covers domestic business-to-business invoicing. Selling to consumers is a different question, and so is selling abroad.

What actually changes for you

If you invoice other businesses, the honest answer is: probably less than you fear, and almost none of it is your job.

The change is in how the invoice is issued and transmitted. In practice that is a property of the software your accountant already uses, or the invoicing tool you already type into. Most Greek accounting packages have been preparing for this for two years. For a lot of small businesses, the mandate arrives as a software update and a slightly different screen.

Where it genuinely bites is if you currently issue invoices by hand. A pad of paper, a Word template, an Excel file you’ve had since 2016. That stops being sufficient, and there is a real deadline attached.

What it does not change

If you only sell to the public, this specific mandate is not aimed at you. A cafe ringing up coffees is not issuing B2B invoices.
Your website has nothing to do with it. I want to be direct about this because you will shortly start getting emails implying otherwise. A website is not an invoicing system, this is not a website problem, and anyone selling you a website on the strength of an e-invoicing deadline is selling you something you do not need for that reason.
It is not a new tax. Nothing about what you owe changes. This is about the format invoices travel in.

The one conversation to have

Ask your accountant exactly this:

From October, am I covered for B2B e-invoicing by the software we already use, or do I need to change something before then?

That is the whole question. There are three possible answers and all of them are fine to hear in July:

“You’re already covered, it’s handled in the software.” Most likely. Nothing to do.
“You’ll need to switch how you issue invoices.” Then you have two months, which is enough, and your accountant will tell you what to move to.
“This doesn’t apply to you.” Also common, if you don’t invoice other businesses.

The reason to ask now rather than in late September is not that the work is large. It is that everyone will ask their accountant in late September.

Why I wrote this

Not to sell you anything. We build websites, and a website has nothing to do with e-invoicing.

I wrote it because I went looking for a plain explanation on behalf of a client and could not find one. Every result was a compliance vendor pitching an enterprise integration platform. A rule that applies to every business in the country in October should have an explanation aimed at the businesses that are actually going to be surprised by it, and it did not have one.

Sources, all publicly available: Law 5222/2025; the phase dates and scope as documented by EDICOM, ecosio, Zone & Co and others as of July 2026. Checked before publishing, but rules change and deadlines slip — confirm the current position with your accountant rather than with a website.