Electronic Invoicing and the SDI: A Practical Guide for VAT-Registered People in Rome

In a nutshell

Since 2019, paper invoices between VAT-registered parties in Italy have no legal standing. Every invoice must be in XML format and pass through the Sistema di Interscambio (SDI), the official exchange platform of Agenzia delle Entrate (Italy's tax-revenue agency). From 1 January 2024, this obligation extends to flat-rate taxpayers as well, regardless of their turnover.

At a glance

Cost	SDI: free. Software: €0 (Agenzia delle Entrate portal) up to €300/year. Preservation: free with Agenzia delle Entrate, €30–€100/year with third-party services.
Timeline	Transmission: instant. SDI response (delivery confirmation or rejection): within 5 days. Invoice must be issued within 12 days of the transaction.
Where in Rome	Everything online: Fatture e Corrispettivi portal with SPID (Italy's digital identity for accessing online public services), CIE (Italian electronic ID card), or CNS
Documents needed	Active Partita IVA, PEC (certified email — legally valid in Italy), SPID or CIE, client's recipient code

How the Sistema di Interscambio works

The SDI is not a website where you "upload" an invoice the way you would attach a file to an email. It is an automated government system that does three things in sequence: it receives your invoice, validates it, then delivers it to your client.

When you submit an invoice, the SDI checks within seconds whether the XML format is valid, whether your Partita IVA is active, and whether the client's recipient code exists. Within 5 days you receive one of three outcomes:

• Delivery receipt (RC): the invoice has reached the client.
• Failed-delivery receipt (MC): the client could not be reached, but the invoice is available in their Cassetto Fiscale (the tax authority's online personal-records area).
• Rejection notice (NS): there is a technical error. You have 5 days to correct it and resubmit with the same number and date.

A PDF invoice sent by ordinary email does not pass through the SDI and does not exist as far as the tax authorities are concerned — even if the client accepts it and pays.

Who must comply — and who doesn't

Everyone holding a Partita IVA (Italian VAT number — required to invoice as a self-employed worker or business) is covered: companies, professionals, tradespeople, retailers, the self-employed, and flat-rate taxpayers from 1 January 2024.

The exceptions are narrow. Doctors, pharmacists, and opticians who transmit data to the Sistema Tessera Sanitaria (the national health-card data system) issue paper or PDF invoices to patients — those records go to STS, not through the SDI. Non-residents without a fixed establishment in Italy and certain farmers under the exemption regime are also excluded.

For invoices to private individuals (people without a Partita IVA), use the recipient code "0000000" (seven zeros): the invoice still passes through the SDI and the client can find it in their Cassetto Fiscale.

How to issue your first electronic invoice

The cheapest route is the Agenzia delle Entrate's free portal, Fatture e Corrispettivi. Log in with SPID, CIE, or CNS, then go to "Fatturazione Elettronica" and create a new invoice.

The essential fields to fill in are:

• Document type: TD01 for a standard invoice, TD04 for a credit note
• Client details: Partita IVA or Codice Fiscale (Italian tax ID — your personal 16-character code, used for almost everything), business name, recipient code or PEC
• Line items: description of the service or product, quantity, price, VAT rate
• Tax regime: if you are on the flat-rate regime, enter RF19 and nature code N2.2, with the statement "Operazione effettuata ai sensi dell'art. 1, commi 54-89, L. 190/2014 — regime forfetario"

If you issue flat-rate invoices above €77.47, you must add a virtual marca da bollo (revenue stamp — a €2 duty on official documents) of €2, paid in aggregate via F24 (the universal Italian payment form for taxes and contributions) using tax code 2501.

After reviewing the preview, submit the invoice and wait for the confirmation in the "Consultazione" section.

The recipient code: what it is and how it works

Before issuing an invoice, ask your client for their 7-character recipient code (codice destinatario). This identifies which channel the client uses to receive invoices: they get it from their accounting software (Aruba, FattureInCloud, etc.) or by registering it in their Agenzia delle Entrate personal area.

If the client is a public administration body, the code is called the Codice Univoco Ufficio (6 characters) and can be found on the IPA — Indice della Pubblica Amministrazione directory.

You can also use the client's PEC address as an alternative delivery route: the SDI sends the invoice as an XML attachment.

Digital preservation: saving the file is not enough

All invoices must be kept for 10 years. But downloading the PDF or keeping the XML in a folder on your computer is not sufficient. Digital preservation requires an electronic signature and a timestamp, in compliance with DM 17/06/2014.

The simplest solution is to activate the free preservation service from Agenzia delle Entrate, available on the Fatture e Corrispettivi portal. You need to opt in once — it is not automatic. Alternatively, paid software (€30–€100/year) can handle compliant preservation for you.

Mistakes to avoid

1. Sending the XML file by email without going through the SDI. An invoice that bypasses the exchange system has no tax-law standing, even if the client receives and pays it.
2. Not activating digital preservation. Keeping the file on your desktop is not enough. Activate the free Agenzia delle Entrate service the first time you access the portal.
3. Forgetting the €2 stamp duty on flat-rate invoices. It accumulates quarterly and is paid via F24. If you skip it, Agenzia delle Entrate will recover it with interest.

Special cases

Invoice rejected by the SDI: each rejection code points to a specific problem. The most common are: client's VAT number no longer active (00200), non-existent recipient code (00400), and invoice number already used (00417). Correct the issue and resubmit within 5 days, keeping the same number and date.

Invoices to foreign clients (EU or non-EU B2B): from 2022, the old quarterly esterometro (foreign-transaction report) no longer exists. Cross-border transactions are now reported through the SDI using specific document types: TD17 for service purchases, TD18 for intra-EU goods, TD19 for goods under art. 17.

Reverse charge: in transactions subject to reverse charge (construction, gold, etc.) the client integrates the VAT with a self-billing document TD16.

Official sources

• Agenzia Entrate — Electronic invoicing
• Fatture e Corrispettivi portal
• FatturaPA.gov.it
• Agenzia Entrate — Electronic invoice guide (PDF)
• IPA — Indice della Pubblica Amministrazione

Legal references: DLgs 127/2015 art. 1, Legge 205/2017, Provvedimento AdE 30/04/2018 n. 89757, DL 36/2022 art. 18, DL 73/2022 conv. L. 122/2022, DM 17/06/2014, DPR 633/1972 artt. 21 e 21-bis.