What is e-invoicing and how does the SdI system work?

E-invoicing is the requirement, in force in Italy since 2019 for almost all transactions between VAT-registered residents, to issue every invoice as structured data (XML, the FatturaPA schema) rather than as a PDF or paper document, and to transmit it through the Sistema di Interscambio (SdI), the public platform run by the Agenzia delle Entrate that receives, formally validates and delivers every invoice to its recipient. The technical point that sets this obligation apart from a simple format change: an XML file is data a program can read, not an image of a document. A PDF holds a layout meant for a human eye; a FatturaPA XML holds separate fields (invoice number, date, the customer's VAT number, line items with product code, quantity, VAT rate) that software can read, validate and import without anyone retyping them. That is why the SdI can validate every invoice before delivering it: it checks the file's structure, not its content the way a person would read it.

See also: Legal Digital Preservation (Italy) · The CAD-regulated process that keeps a digital document authentic, unaltered and legally valid over time.

How the technical flow works

The supplier generates the XML file, from its accounting software, a web portal or an intermediary, and sends it to the SdI. The system runs formal checks (VAT number, mandatory fields, totals matching declared VAT rates) and within minutes returns a rejection receipt, stating the reason, or delivers the invoice to the recipient through its own channel (certified email, the software's recipient code, the Fatture e Corrispettivi portal). The XML file passed through the SdI is the legally relevant document: the on-screen view in the accounting software is only a convenience reading of that data. This is where the obligation stops being a formality and becomes structured data exchange between systems, the same logic behind EDI, applied by law to every Italian business.

Preservation and the EU direction

Issuing and receiving the invoice does not close the obligation: the XML file and its receipt must be kept in a legally valid way, a distinct process called digital long-term preservation, which follows the AgID guidelines and, for tax documents, also the Ministry of Economy and Finance decree of 17 June 2014, and is different from simply saving the file to a disk. Italy anticipated a path the European Union is now generalizing through the VAT in the Digital Age (ViDA) package, adopted on 11 March 2025, which from 1 July 2030 introduces digital reporting based on e-invoicing for intra-EU B2B transactions.

A concrete example

A manufacturing company issuing two hundred invoices a month treats the SdI as an invisible step: the software generates the XML, transmits it, receives the outcome. The problem appears when that company wants to use its own invoice data, reconstruct revenue by customer, feed a management control dashboard, and finds the software only exposes it through rigid reports or manual exports. The XML invoices already exist as clean data: the work is not "digitizing invoices", it is connecting that flow to a reporting system or a data warehouse, avoiding the manual re-entry of data that was already machine-readable at the source.

Why it matters for decision makers

E-invoicing has made every Italian business the owner of a history of structured, verified commercial data, without anyone having had to design a system to create it. Whoever treats the SdI as a tax formality to delegate to an accountant leaves that data on the table; whoever treats it as a source already ready for analysis folds it into reporting and decision processes with modest technical effort, because the structure already exists. The choice of accounting software, and above all its ability to expose that data outward, therefore matters longer term than it seems to at the moment of purchase.

This entry is informational and does not constitute tax or legal advice: for decisions on your obligations, involve your accountant or legal counsel.