Electronic Invoicing and the SDI: A Practical Guide for Businesses and Flat-Rate Taxpayers in Rome

In a nutshell

Since 1 January 2024, anyone holding a Partita IVA (Italian VAT number — required to invoice as a self-employed worker or business) must issue electronic invoices through the Sistema di Interscambio (SDI), the official exchange platform run by Agenzia delle Entrate (Italy's tax-revenue agency). This applies to flat-rate taxpayers too, regardless of how many clients they have or how much they earn. An invoice is no longer a PDF or a sheet of paper: it is an XML FatturaPA file that must pass through the SDI before it reaches your client.

At a glance

Cost	Free via the Agenzia delle Entrate portal. Third-party software: €4–€30/month
Issue timeline	Immediate invoicing: within 12 days of the transaction. Deferred invoicing: by the 15th of the following month
Where in Rome	Everything is done online. Agenzia delle Entrate offices for in-person support (7 local branches)
Documents needed	SPID (Italy's digital identity for accessing online public services), CIE (Italian electronic ID card), CNS, or Entratel/Fisconline credentials to log in to the portal

Who must comply — and who doesn't

The obligation was rolled out in stages:

• From 2019: limited companies (Srl, Spa, Snc, Sas), professionals, and sole traders on the standard or simplified VAT regime
• From July 2022: flat-rate taxpayers with revenues above €25,000 in the previous year
• From 2024: all flat-rate taxpayers, with no revenue threshold at all

The only people exempt are doctors, pharmacists, physiotherapists, and other healthcare professionals for invoices issued to private patients that feed into the Sistema Tessera Sanitaria (the national health-card data system — a privacy restriction prevents those from going through the SDI). For B2B invoices, even they must use the SDI. Non-Italian entities without an Italian Partita IVA are also excluded.

If you hold an Italian Partita IVA — even as a foreign national — you are required to comply. Full stop.

How the SDI works

The Sistema di Interscambio is a platform managed by Agenzia delle Entrate and Sogei. Think of it as a "certified postal service for invoices": you send the XML file, the SDI checks it, and then delivers it to your client.

The process step by step:

1. You generate the XML FatturaPA file using your software or the online portal
2. The SDI validates the structure, your Partita IVA, and the recipient code
3. If everything checks out, the invoice reaches your client within minutes
4. If there is an error, you receive a rejection notice with a specific error code (e.g., 00301 = invalid VAT number)

To receive invoices, your client gives you their codice destinatario (a 7-character routing code) or their PEC (certified email — legally valid in Italy). If you invoice a private individual without a Partita IVA, you use the placeholder code 0000000 and still hand them a paper or PDF copy.

You can register your preferred delivery address on the Fatture e Corrispettivi portal: from that point on, all invoices addressed to your Partita IVA arrive automatically on the channel you selected.

Special rules for flat-rate taxpayers

If you operate under the flat-rate regime (Legge 190/2014), a few things are different from a standard VAT holder:

• You do not charge VAT on your invoices. You must include the following statement: "Operazione effettuata ai sensi dell'art. 1, commi da 54 a 89, della Legge n. 190/2014"
• You use the VAT nature code N2.2 in the XML file
• For invoices above €77.47, you must apply a marca da bollo (revenue stamp — a €2 duty you pay on official documents) of €2 (tax code 2501). Payment is made quarterly by the 16th of the second month following each quarter

The marca da bollo is not optional: if you skip it, the penalty is 2 to 5 times the unpaid amount.

How to issue an electronic invoice

You have four main options:

Fatture e Corrispettivi portal (free): log in at ivaservizi.agenziaentrate.gov.it using SPID, CIE, or Entratel credentials. Fill in the invoice online, the portal generates the XML and sends it to the SDI automatically. You can also activate free 10-year digital preservation directly here.

FatturAE app (free): available on iOS and Android, allows you to issue invoices from your phone in a simplified interface.

Private accounting software: Aruba, Fatture in Cloud, Fatture24, TeamSystem, and others. Prices start at a few euros a month; flat-rate taxpayers with few invoices can find free plans with limitations. The advantage is integration with your bookkeeping and automatic preservation.

Your accountant: if you already have a commercialista (Italian tax accountant / bookkeeper), they often handle invoice submission as part of their monthly service. Check what is included in your fee.

Preservation: 10 years — but only if done properly

Electronic invoices must be kept for 10 years using a compliant digital preservation process. Saving the XML files to your desktop is not enough: the law requires a digital signature, a timestamp, and a documented process.

You have two options:

• Free preservation via Agenzia delle Entrate: activate it on the Fatture e Corrispettivi portal by signing the service agreement. Invoices that pass through the SDI are then preserved automatically.
• Private accredited preservers (AgID-listed): Aruba, InfoCert, Namirial, and others. These are paid services but offer additional features.

Skipping proper preservation can result in a fine of €1,000 to €8,000.

Mistakes to avoid

1. Wrong recipient code. The invoice may still be delivered if the client has registered their preferred address on the Agenzia delle Entrate portal. If they haven't, the SDI sends a failed-delivery receipt and the client must download the invoice manually. Always ask for the correct code before issuing.
2. Resubmitting a rejected invoice immediately with the same number. After a rejection you have 5 days to correct the invoice and resubmit it with the same date and number. Beyond 5 days, you must issue a brand-new invoice with the current date and a different sequential number.
3. Forgetting the €2 revenue stamp as a flat-rate taxpayer. Every invoice above €77.47 requires it. You won't notice the accumulation straight away, but the Agenzia delle Entrate's automated checks will.

Special cases

Cross-border transactions: for sales to EU or non-EU clients, use the recipient code XXXXXXX in the XML file. For purchases from foreign suppliers, you must issue a self-billing document or integration using document types TD17, TD18, or TD19, by the 15th of the month following the transaction.

Credit notes: issued with document type TD04, following the same process as a regular invoice. You must reference the original invoice (number and date).

Invoices to public bodies: if you invoice a public administration entity, you use the codice univoco ufficio IPA — a 6-character office code found on the IPA register (e.g., UFB1RM for certain Rome City Council offices). The obligation to issue electronic invoices to public bodies has been in force since 2014.

Official sources

• Agenzia Entrate — Electronic invoicing
• FatturaPA portal
• Fatture e Corrispettivi — log in with SPID
• Agenzia Entrate — Digital preservation
• FatturAE app — info
• Stamp duty on electronic invoices
• Normattiva — DLgs 127/2015
• AgID — Accredited digital preservers

Legal references: DLgs 127/2015, Legge 205/2017 art. 1 commi 909-928, DL 36/2022 art. 18, DPR 633/1972, Provvedimento Agenzia Entrate 89757/2018, DM 17/06/2014, DPR 642/1972.