# NFE-591

Source: https://xmlvalid.com/rules/NFE-591

> Rejeição: Informado CSOSN para emissor que não é do Simples Nacional (CRT diferente de 1 ou 4) [nItem: …] (CRT …, CSOSN …).

- Level: error
- Rule sets: SEFAZ authorisation rules of NF-e 4.00 MOC 7.0 Anexo I, NTs up to 2026.010
- Context: `nfe:infNFe/nfe:det`
- Test: `$crt = ('1', '4') or not($csosn)`

In English: An issuer outside the Simples Nacional (CRT other than 1 and 4) gives a CSOSN.

Validate a document against these rules: https://xmlvalid.com/validate