You must issue the following sales documents:

1. Sales invoice: it is an item issued for any sale of goods and provision of services to entities, within the country or to any other country as well as in any transaction subject to VAT.

Invoice issuance time

• In the case of the sale of goods or the provision of services, the invoice shall be issued no later than the 15th day of the following month of the delivery or dispatch of goods or the completion of the service as appropriate.
• In the case of continued supply of goods, service or construction work, the invoice shall be issued by the 15th day of the following month from the period in which part of the relevant remuneration becomes chargeable for the goods or services provided or part of the work completed.
• In the case of obtaining the right to receive a service, the invoice is issued with the acquisition of this right.

You can also issue:

• Credit invoice: in case of discounts, refunds or other differences.
• Simplified invoice: when the amount of the invoice does not exceed one hundred (100) euros or when it is a document or message that amends and refers to an original invoice.
• Summary invoice: when referring to different supplies of goods or services

Self-billing:
the invoice is issued by the recipient of the goods or services.

2. Receipt of retail sale or proof of provision of services: for each sale of goods or services to private consumers, instead of an invoice you should issue a retail item (retail receipt or proof of service) and a copy of it is delivered, sent or made available to the customer.

• The issuance of retail sales data is carried out using electronic tax mechanisms, which follow specific technical specifications, information and operational characteristics, in order to ensure the authenticity and integrity of the issued retail data.
• Retail data may be issued using the services of an electronic retail data provider instead of using electronic tax mechanisms. (see related link here).
• You must declare the tax electronic mechanism, within ten (10) days from the start of its use, electronically on the website of IAPR (see the relevant link  here) or if the 10 days have passed, you must submit the relevant form (Β2) in the competent tax office.   

Time of issuance of retail data

• In case of sale of goods, at the time of delivery or beginning of dispatch.
• In the case of provision of services, upon completion of the provision of the service.
• In the case of obtaining a right to receive a service, by obtaining this right.
• In the case of continued provision of goods, service or construction work, when part of the remuneration becomes due for part of the service or work completed and in any case with the completion of the service or work.

You can issue in a handwritten way or with other technical means retail data only in the following cases:

a) during an electricity power cut or interruption of the instrument of issuing documents due to a technical problem.

b) if you belong to the categories of entities that are exempt from the use of tax mechanisms  (ΠΟΛ.1002/31-12-2014).

Indicatively, the following professions are mentioned: owner of beauty salons, gyms, parking lots, veterinarian, notary, lawyer, etc. as well as transactions outside the business establishment of the person liable, sale of goods or provision of services from fixed points after authorisation of the relevant services.

c) if you exceptionally make occasional retail sales.
 

Learn that:

In case of non-operation of the document issuing equipment due to a technical problem, you must take all necessary measures to restore it without undue delay.

3. Electronic invoice: 
it is any invoice as well as retail data item that has been issued and received in electronic form. The use of an electronic invoice is subject to its acceptance, in a printed or electronic way, by the recipient of the goods or services subject to invoicing. Determining of electronic invoice format  here.