00321: Seller's tax number is not in the VAT group
What it means
SdI code 00321 means the seller's tax number (1.2.1.2 CodiceFiscale) belongs to a party that is not a member of the VAT group given in the VAT number.
The usual cause
The invoice uses a VAT group's VAT number with the tax number of a party outside that group.
How to fix it
Use the tax number of the group member that issues the invoice, or the right VAT number for the seller, and send the file again.
Elements the check reads
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1.2.1.2 CodiceFiscale
The code as published
Read the official document . Source: Elenco dei controlli effettuati sul file fattura del Sistema di Interscambio, version 2.0, published by Agenzia delle Entrate, fatturapa.gov.it, read on 8 November 2026.
Klarbon explains each code in its own words; the official wording is in the document linked above.
Look at your file
Open the invoice in your browser to find the fields this code names: Open an Italian FatturaPA invoice. Open an Italian FatturaPA invoice
Other SdI codes
- 00300 Sender's tax number not valid
- 00301 Seller's VAT number not valid
- 00302 Seller's tax number not valid
- 00303 Tax representative's VAT number not valid
- 00304 Tax representative's tax number not valid
- 00305 Buyer's VAT number not valid
- 00306 Buyer's tax number not valid
- 00311 Recipient code not valid
- 00312 Recipient code not active
- 00320 Seller's VAT number and tax number do not match
- 00322 Tax number missing with a VAT group number
- 00323 Seller's VAT number closed more than five years ago
- 00324 Buyer's VAT number and tax number do not match
- 00398 Central office code used where a specific office exists
- 00399 Private-sector format used for a public body