The numbering of the invoice based on the date of issue (e.g. 1 June 2020: 20200601) and an additional hexadecimal progressive code (using symbols from 0 to 9 for the first ten digits, and then the letters from A to F for the next six digits, for a total of 16 symbols: e.g. 0001, 0002, etc.000A, 000B), is not compatible with the “sequentiality” requirement and does not guarantee compliance with EU and national legislation.


Normative statement

This is the clarification contained in the reply to the request for consultation no. 505 of 29 October 2020, regarding the numbering of invoices.

The Revenue Office has reminded that, as of 1 January 2013 (as a result of the provisions contained in Article 21 paragraph 2 letter b) of Presidential Decree 633/72, as replaced by Article 1 paragraph 325 letter d) of Law 228/2012), the invoice must contain a “progressive number that uniquely identifies it”. Numbering systems other than progressive numbering systems per calendar year are, therefore, also admissible, provided that the conditions of uniqueness and progressiveness of the numbers assigned to the invoices are respected.

However, the numbering referring to the “date of the invoice itself” is hardly practicable in the context of electronic invoicing, since the date of issue coincides with the date of transmission of the XML file to the SdI, and may, therefore, be after the date of execution of the operation.

Therefore, as pointed out by the Agency, an invoice numbering system structured on the progression of the date of issue, is unsuitable to comply with the sequentiality required by the EU provisions, since a “date jump” may occur in case of failure to issue invoices in some days.



Obstacles to the functions of control

This circumstance could prevent the Financial Administration:

  • the control of the correspondence between the numbering of the documents and their annotation in the accounting records, “necessary to avoid unjustified intervals in the order of issue and annotation”;
  • the correct reconstruction of active transactions.

Finally, the practice document stresses that the absence of a sequential order would not even allow the Revenue Office to correctly prepare the drafts, as required by art. 4 of Legislative Decree no. 127/2015, starting from VAT transactions carried out from 1 January 2021:

  • periodic VAT settlements,
  • the registers referred to in Articles 23 and 25 of Presidential Decree 633/72 and
  • of the annual VAT declaration.



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