Starting July 2026, Brazil will issue a new format for the CNPJ — the national tax ID for companies. For the first time, the identifier will combine letters and numbers: the so-called alphanumeric CNPJ. The change was established by Normative Instruction RFB No. 2,229/2024 and applies only to new registrations.
If you build software that integrates with Brazilian systems, process invoices, or maintain anything that validates a CNPJ, this is one of the most consequential format changes of the decade for your work. This guide explains what changes, what does not, and how to generate CNPJs in the new format to test your systems before the deadline.
What actually changes
The CNPJ keeps its 14 positions, but the composition changes. The first twelve positions (root + branch order) will accept letters A–Z in addition to digits 0–9. The final two positions — the check digits — remain numeric.
In practice, a CNPJ that today reads 12.345.678/0001-95 could, in the new format, look like 12.ABC.678/0001-95. The visual mask (dots, slash, hyphen) stays identical, which eases the transition.
What does NOT change
Here is the reassuring part for most companies:
Existing CNPJs will not be altered. No company needs to re-register, and no current number will be invalidated. Numeric CNPJs remain fully valid and will coexist with the new ones indefinitely.
Issuance is also gradual and random. Even after July 2026, a new registration may still receive a fully numeric CNPJ — letters are assigned by the tax authority's systems based on combination availability.
Why the change happened
The reason is simple: exhaustion. With millions of new companies registered in Brazil each year, the purely numeric combinations were approaching their mathematical limit. Adding letters dramatically expands the available combination space, ensuring decades of new registrations without another overhaul.
The tax authority was explicit in dismissing rumors: the change is purely about registration capacity. It has no connection to financial tracking, tax changes, or any impact on payment systems.
The part that affects developers: the check digit
This is the technical detail that matters for anyone maintaining systems. The check-digit calculation must be adapted. In the old format, the check digit is computed directly from numeric digits. In the alphanumeric format, each character (including letters) is converted to a numeric value before the mod-11 calculation — typically by subtracting 48 from the character's ASCII code, so '0' maps to 0, '9' to 9, 'A' to 17, and so on.
This means any CNPJ validation that treats the field as strictly numeric will break with the new numbers. Invoice systems, e-commerce platforms, ERPs, and payment gateways need to update both parsing and digit validation.
How to prepare now
The best way to ensure your systems are ready is to test them with CNPJs in the new format before they appear in production. That is exactly what a CNPJ generator is for: producing structurally valid numbers — with a correct check digit — to populate test environments, validate forms, and exercise your parsing rules.
Use our CNPJ generator to create valid numbers in both the traditional numeric format and the new alphanumeric one, and confirm that your validation accepts both correctly. Generating synthetic test data is the safe way to prepare — without using real companies' CNPJs in development environments.
Note: CNPJs generated for testing are structurally valid but do not correspond to real registered companies. Use them only for development and QA, never to represent a real legal entity.
Summary
From July 2026, new CNPJs may contain letters; existing ones stay the same; and the check-digit calculation changes to accommodate alphanumeric characters. If you maintain any system that validates a CNPJ, the time to test is now — before the first number with a letter reaches your database.
Rules verified 2026-06-04, based on IN RFB No. 2,229/2024. Always confirm official tax authority communications for implementation details.