Italy's FatturaPA: what makes an invoice valid (TD01/TD04, Natura, SDI)

Italy's e-invoicing didn't wait for the EU-wide EN 16931 push — it's been mandatory for domestic B2B and B2C invoicing since 2019, running on its own national XML vocabulary: FatturaPA. If you're integrating with an Italian counterparty or building for the Italian market, here's what the format actually asks of you.

Not a UBL/CII profile

FatturaPA is a proprietary XML schema, not an EN 16931 syntax. It bundles what other formats keep separate — transmission-envelope metadata (who's sending, to what recipient code) and invoice content — into one document. That's a structural difference worth internalizing before you start mapping fields: there is no "convert UBL to FatturaPA" the way there is UBL↔CII, because the models aren't a superset/subset of each other.

TipoDocumento: what kind of document this is

The TipoDocumento code says what the document is. The two you'll use almost always:

• TD01 — standard invoice (fattura).
• TD04 — credit note (nota di credito).
• TD05 — debit note (nota di debito) also exists, but it has no automatic mapping from a generic invoice type code; it has to be requested explicitly.

Anything past these three (advance invoices, self-invoices, fee notes and more) is a different animal with its own rules — worth rejecting explicitly rather than approximating if your engine doesn't fully support it.

Natura: why a line has no VAT rate

Natura codes explain why a line is VAT-exempt, excluded, or reverse-charged — Italian VAT law requires the reason, not just a zero rate. Common mappings from a generic invoice model's VAT category:

The N2.2 mapping is the one that matters most for small Italian businesses: it's what unlocks invoices for the popular regime forfettario flat-rate scheme, where lines carry no VAT at all.

The Italy-only fiscal extras

A handful of fields exist only in the Italian fiscal system, with no home in a generic cross-border invoice model:

• ritenuta d'acconto — withholding tax, common for professional services invoices.
• bollo — a revenue stamp, required on certain VAT-exempt invoices above a threshold.
• cassa previdenziale — a professional pension fund contribution, added on top of the fee for regulated professions (lawyers, engineers, accountants each have their own fund code, TC01 through TC18).

These are typically modeled as extras alongside a canonical invoice rather than bolted onto the core model — Italy-specific line items that don't mean anything outside Italian tax law.

How it actually reaches the buyer: SDI

FatturaPA invoices don't go directly to the buyer. They're submitted to SDI (Sistema di Interscambio), a government clearance system, using either a 7-character recipient code (codice_destinatario) or the buyer's certified email (PEC). SDI validates, routes and only then delivers. formato_trasmissione distinguishes private recipients (FPR12) from public administration (FPA12).

curl -X POST "$BASE/v1/validate/facturapa" \
  -H "Content-Type: application/xml" --data-binary @fattura.xml

A sample TD01 invoice and TD04 credit note, already validated, are available on our samples page — and the full field-by-field reference (including all optional fiscal extras) lives on the FatturaPA landing page.