00400: Nature code missing on a line at zero VAT
What it means
SdI code 00400 means a line has a VAT rate of zero (2.2.1.12 AliquotaIVA) but no nature code (2.2.1.14 Natura).
The usual cause
A line with a VAT rate of zero must include a Natura code.
How to fix it
Add the right Natura code to each zero-rate line and send the file again.
Elements the check reads
-
2.2.1.14 Natura -
2.2.1.12 AliquotaIVA
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
- 00401 Nature code on a line with VAT
- 00403 Invoice date in the future
- 00411 Withholding data missing for lines with withholding
- 00413 Nature code missing on a pension fund contribution at zero VAT
- 00414 Nature code on a pension fund contribution with VAT
- 00415 Withholding data missing for a pension fund contribution
- 00417 Buyer has neither VAT number nor tax number
- 00418 Credit note dated before the invoice it corrects
- 00419 VAT breakdown missing for a rate
- 00420 Reverse charge nature with split payment
- 00421 VAT amount not calculated correctly
- 00422 Taxable amount not calculated correctly
- 00423 Line total not calculated correctly
- 00424 VAT rate not given as a percentage
- 00425 Invoice number has no digits
- 00427 Recipient code length does not fit the format
- 00428 Format does not match the version attribute
- 00429 Nature code missing in a VAT breakdown at zero rate
- 00430 Nature code in a VAT breakdown with a rate
- 00437 Document discount without a percentage or amount
- 00438 Line discount without a percentage or amount
- 00443 VAT rate with no matching summary
- 00444 Nature code with no matching summary
- 00445 Generic nature code no longer allowed
- 00471 Seller and buyer must differ for this document type
- 00472 Seller and buyer must be the same for this document type
- 00473 Seller's country not allowed for this document type
- 00474 Zero VAT rate not allowed for this document type
- 00475 Buyer's VAT number required for this document type
- 00476 Neither VAT country code identifies Italy
- 00477 Declaration of intent no longer valid