Greece tax regulations

Starting from December 31st 2024, all point-of-sale systems in Greece must be integrated with a payment terminal and an e-invoicing system. This ensures that all in-person transactions are recorded, matched to the sales of goods, and invoiced to the tax authorities (AADE).

To stay compliant with the Greek tax regulations, we accept the unique signature generated by your selected e-invoicing system and attach it to the unique identifier of the transaction. You can then pass the result the tax authorities, therefore proving the sale of goods for that transaction.

Requirements

Before you begin, take into account the following requirements, limitations, and preparations.

How it works

1. You start a transaction from your POS app.
2. Your POS app retrieves a unique signature from the integrated e-invoicing system.
3. Your POS app sends a payment request to the Adyen payment terminal with the e-invoicing signature.
4. The payment terminal checks the e-invoicing signature using the public key of the e-invoicing system.
5. We process the payment and the terminal returns the response with the unique transaction identifier for that e-invoicing signature.
6. Your POS app sends the transaction result to the e-invoicing system which forwards the result to the Tax office.

Integrate with an e-invoicing provider

Adyen is able to receive the e-invoicing details in the Terminal API request and check them with the public key of the e-invoicing provider. However, you need to integrate your POS app with an e-invoicing system of your choice. How you retrieve the e-invoicing signature and send the transaction result is up to you.
Because e-invoicing systems use different message structures, you should refer to the integration documentation of the e-invoicing provider you selected.

Adyen supports the payment flow integrated through all the e-invoicing providers listed by AADE.

Make a payment

1. From your POS app, retrieve the signature from the e-invoicing system for the payment terminal you will use and the purchase amount of the transaction.

2. Create a aadeData JSON object with:

   • aadeProviderId: the unique identifier of the e-invoicing provider. Find the right provider code on the AADE website.
   • aadeProviderSignature: the unique signature for the payment request retrieved from the e-invoicing system.

     Do not send aadeProviderSignature in any other request other than the payment request.

   • aadeProviderSignatureData: the data used to verify the signature with the public key of the e-invoicing system.

     The e-invoicing timestamp inside aadeProviderSignatureData must not be older than 24 hours.
     TID in the aadeProviderSignatureData must be set to the POIID of the payment terminal.
     The aadeProviderSignature must be unique for every transaction.

3. Encode the aadeData JSON object to Base64. You will pass the resulting string in SaleData.SaleToPOIData.

4. Make a payment request with the Base64-encoded JSON object in the SaleToPOIData:

   The AmountsReq.RequestedAmount inside the PaymentRequest must be equal to or lower than the amount payable in the aadeProviderSignature.

5. If the payment is successful, from the AdditionalResponse of the payment response save the following:

   • aadeTransactionID: the unique identifier of the payment
   • aadeProviderSignature: the signature from the e-invoicing system

6. From your POS system, send the aadeTransactionID and the aadeProviderSignature to the e-invoicing system.

Refunds

If you need to refund a payment to a shopper, you can do a standard referenced refund using the ReversalRequest. To make an unreferenced refund, you need to include another unique signature from the e-invoicing system inside the Base64-encoded aadeData JSON object in the SaleToPOIData.

Errors

During the payment flow, Adyen payment terminals perform the following validations:

• Checks if the aadeProviderSignature is unique for each payment request.
• Checks if the timestamp in the aadeProviderSignatureData is older than 24 hours.
• Checks if the transaction amount is lower or equal to the amount payable in the aadeProviderSignatureData.
• If the terminal identifier in the aadeProviderSignatureData (TID) matches the POIID from the MessageHeader.

If any of these validations fails, the payment response returns an error with a Base64-encoded error message in the AdditionalResponse:

See also