Mandatory B2B E-Invoicing in Greece 2026: A Complete Guide for Businesses
If your business issues invoices to other businesses in Greece, October 1st, 2026 is a date you need to mark on your calendar. From that point on, B2B electronic invoicing becomes mandatory for all businesses – regardless of size or sector.
The good news: businesses that prepare early don’t just comply with the law – they also unlock significant financial benefits that won’t be available later.
In this article you’ll find everything you need to know: exactly what changes, the key deadlines, what AADE’s incentives cover, and how Protogramma can support you every step of the way.
What is B2B e-invoicing and why is it becoming mandatory
Electronic invoicing (e-invoicing) is the issuance and transmission of invoices in a structured digital format through approved systems, with automatic connection to AADE’s myDATA platform. It’s not simply sending a PDF invoice by email – it’s a standardized digital flow that eliminates manual entry and dramatically reduces errors.
The mandatory rollout is part of Greece’s broader digital economy strategy, aligned with the European directive to reduce tax evasion and simplify fiscal obligations. Based on a joint decision by the Deputy Minister of National Economy and Finance and the Governor of AADE (September 2025), a clear implementation timeline has been set for all businesses.
Which businesses are affected
The obligation applies to every business conducting B2B transactions in Greece, meaning any company that issues invoices to other businesses for the sale of goods or provision of services.
More specifically:
- Transactions between Greek businesses: Mandatory issuance of electronic invoice and mandatory acceptance by the receiving business.
- Transactions with businesses outside the EU: Mandatory issuance of electronic invoice. If the foreign recipient does not accept it, the invoice may be sent by alternative means.
- Transactions with EU businesses: Issuance of electronic invoices remains optional.
There is no exemption based on business size – the obligation applies to small and medium businesses as well as larger companies, with the only difference being the implementation timeline.
Timeline – Key dates
Phase A – Large businesses (turnover over €1,000,000 for 2023)
- 2/2/2026: Start of mandatory application
- 2/2 – 31/3/2026: Gradual transition period
Phase B – All other businesses
- 1/10/2026: Start of mandatory application
- 1/10 – 31/12/2026: Transition period for ERP integration
Key dates for early readiness benefits
- By 30/6/2026: Free activation (valued at €100) + 3 months free use
- By 31/7/2026: Last opportunity to qualify for AADE tax incentives
AADE tax incentives for early adoption
One of the most significant elements of the legislation is the incentives AADE offers to businesses that join ahead of the mandatory deadlines. These are not symbolic benefits – they are substantial tax reliefs.
For businesses that activate by July 31st, 2026:
- 200% depreciation of expenses for technical equipment and software in the year of purchase. In practice: if you purchase equipment worth €1,000, you can deduct €2,000 from your taxable income.
- +100% surcharge on costs for the production, transmission and electronic archiving of invoices for the first 12 months of issuance.
These incentives apply to businesses with annual turnover up to €1,000,000 (for fiscal year 2023) that join a certified e-invoicing Provider within the deadlines. The prerequisite is completing the AADE declaration, signing the Provider contract and beginning issuance within the specified timeline.
What you gain by joining before June 30th, 2026
Beyond the AADE tax incentives, early adoption through a Provider unlocks additional benefits available exclusively for activations by June 30th, 2026.
Free Activation Service, valued at €100 Activating through a Provider involves several steps: AADE declaration, contract preparation, production key issuance. Normally, this service is charged as a one-off fee of €100. For activations by June 30th, it is offered completely free of charge – we handle the entire process and deliver the service ready to use.
3 months of free use The annual subscription doesn’t start from the day of activation – but after the three-month free period ends. This gives you time to get familiar with the system, run tests and make sure everything works correctly, with no financial commitment during that period.
A smooth transition, without time pressure Businesses that wait until the last weeks before October 1st face a backlog of requests, tight timelines and an increased risk of errors. Joining early gives you the time you need to make the transition properly.
In summary, for activation by June 30th, 2026:
| Benefit | Value |
|---|---|
| Free Activation Service | €100 one-off |
| 3 months free use | Depends on package |
| 200% depreciation on equipment/software (AADE) | Tax relief |
| +100% surcharge on Provider costs for year 1 (AADE) | Tax relief |
How a business can comply
Every business has two options for fulfilling the e-invoicing obligation:
Option 1: Free AADE application AADE offers the free applications timologio and myDATAapp (for mobile devices). These applications cover basic needs and are suitable for businesses with low invoice volumes or for invoices related to public contracts.
Option 2: Certified e-invoicing Provider For businesses with higher transaction volumes or a need for ERP/accounting system integration, a certified Provider solution offers automation, security and full connectivity with existing management systems.
The benefits of e-invoicing beyond compliance
Mandatory implementation may sound like yet another bureaucratic obligation. In practice, however, e-invoicing brings changes that directly benefit day-to-day business operations:
- Reduced administrative costs: Eliminates printing, postage and physical archiving costs.
- Fewer errors: Automatic transmission to myDATA eliminates manual entry mistakes.
- Faster processing: Invoices reach the recipient instantly and are ready for accounting.
- Pre-filled tax declarations: E-invoicing data is used to automatically pre-fill VAT declarations and the E3 form.
- Better cash flow: Immediate sending and receipt confirmation speeds up the payment cycle.
Frequently asked questions
What happens if I don’t join within the deadlines? Non-compliance after the mandatory application date results in penalties under tax legislation. You will also permanently lose the tax incentives AADE offers for early adoption.
Do I need to change my accounting software? Not necessarily. Most modern ERP and accounting systems support or can be connected to certified e-invoicing Providers. The integration process is covered by the transition period until 31/12/2026.
What is the Activation Service? It is a service that handles the entire setup and activation process: AADE declaration, contract preparation, key issuance and delivery of the service in full operation. For activations by June 30th, 2026, it is offered free of charge (standard value €100).
Does this affect businesses in Cyprus? This specific legislation applies to businesses operating in Greece. Cyprus has a separate regulatory framework. Contact us for information about the obligations applicable to your business.
How Protogramma can help
At Protogramma Informatics, we have 30 years of experience supporting SMEs across Greece and Cyprus. We know that every business has different needs and different systems – and we ensure the transition to e-invoicing happens without disruption to your day-to-day operations.
We handle:
- Assessment of your current systems and selection of the right solution
- The entire Provider onboarding process: AADE declaration, contracts, production keys
- Integration with your existing ERP or accounting system
- Training for your team
- Post-activation support
Contact us today to schedule your activation in time and make the most of the available benefits.
