CNAE Format Validator

CNAE subclass: the 7-digit economic activity code NNNN-N/NN

The CNAE (Classificação Nacional de Atividades Econômicas) is the official Brazilian classification of what a business does, maintained by the IBGE through the CONCLA commission. Its most detailed level, the subclasse, is a 7-digit code written NNNN-N/NN — for example 6201-5/00 (custom software development). This tool checks that structural format.

The CNAE descends from the international ISIC standard but adds two extra digits (the /NN subclass) for Brazilian fiscal detail. Every CNPJ declares a main CNAE plus optional secondary ones, and that choice drives tax regime, Simples Nacional eligibility, licensing and inspection requirements.

Anatomy of 6201-5/00

• Division (62): the first two digits — broad sector (here, IT services).
• Group & class (620, 6201): progressively narrower activity.
• Check digit (5): the fifth digit (-5) is a verifying digit on the class.
• Subclass (/00): the Brazilian two-digit detail; 00 means no further breakdown.

Where it matters

• CNPJ registration: the main CNAE is mandatory and shapes everything downstream.
• Tax regime: some CNAEs are barred from Simples Nacional or trigger ICMS substituição tributária.
• Licensing: environmental, sanitary (ANVISA) and fire-department requirements key off the CNAE.
• Mock data / testing: validating the NNNN-N/NN mask before a Receita/IBGE lookup.

Common pitfalls

• Format ≠ exists: a well-masked code may not be a real CNAE — check the IBGE/CONCLA table.
• Punctuation is cosmetic: 6201500 and 6201-5/00 are the same; normalise before comparing.
• Wrong CNAE = wrong tax: misclassifying activity can exclude you from Simples or attract the wrong ISS/ICMS.
• Main vs secondary: a company can hold many CNAEs; don't assume the first is the only one.

FAQ

Why does CNAE have 7 digits when ISIC has fewer? Brazil appended a 2-digit subclass for finer fiscal granularity beyond the international class.

What is the fifth digit? A check digit on the four-digit class, separated by a hyphen (6201-5).

Can one company have several CNAEs? Yes — one main CNAE plus any number of secondary CNAEs on the CNPJ card.