myDATA & Invoicing
myDATA & Electronic Invoicing: What Every Business Needs to Know
Published · 7 min read · NS Accounting & Tax Office
Electronic invoicing is no longer an optional choice, but a legal obligation affecting practically every business in Greece. With the expansion of the myDATA framework to all businesses from 1 October 2026, many business owners are asking what exactly changes and what they need to do immediately. The NS Tax accounting firm answers the most important questions in this article in a practical and accessible way.
What Is myDATA
myDATA (my Digital Accounting and Tax Application) is AADE’s digital platform through which businesses transmit invoice summaries, income and expense classifications, and payroll entries in real time. The system aims to automatically pre-fill tax returns and reduce tax evasion.
Who It Affects and When
Mandatory electronic invoicing is being introduced in two phases:
- From 2 March 2026: mandatory for businesses with gross revenue above €1,000,000, based on the 2023 tax year
- From 1 October 2026: extended to all remaining businesses, regardless of size or invoice volume
How an Electronic Invoice Is Issued
There is no minimum turnover or invoice threshold that exempts a business from the obligation — even issuing one invoice per week falls under the new regime.
Electronic invoices must be issued either through a certified Electronic Invoicing Service Provider or through AADE’s free applications (Timologio, myDATAapp) for simpler needs. For business-to-business invoices, using a certified provider is now mandatory — a simple direct connection without a provider is not sufficient.
Also read what VAT changes mean for businesses and our guide to the tax obligations of a new business.
5 Practical Preparation Steps for Your Business
NSTAX services for businesses can support your transition in a structured way.
1. Check whether your current software meets the new obligation
Already transmitting data to myDATA does not automatically mean your system also meets the electronic invoicing obligation — a separate check is required.
2. Choose a certified provider early
Your provider should match your invoice volume and the complexity of your activity — do not leave this decision until the last minute.
3. Run test invoices before the deadline
Before the obligation takes effect, test invoice issuance so you can identify any problems in time.
4. Train staff who issue invoices
Pay particular attention to credit invoices, cancellations and special transaction categories, where errors are more common.
5. Consult an accounting firm early
Proper preparation requires both accounting and technical knowledge — an early discussion with your accountant prevents compliance problems.
Need Help Moving to Electronic Invoicing?
NSTAX, an accounting and tax firm based in Athens, guides businesses of every size through proper adaptation to the new myDATA regime. Contact us before the deadline to ensure a smooth transition.
The myDATA implementation framework may be amended by newer AADE decisions. Contact us for the current requirements affecting your business.