Alphanumeric CNPJ Generator

The Alphanumeric CNPJ is the new legal entity registration format approved by the Brazilian Federal Revenue through Normative Instruction RFB No. 2,229/2024. Unlike the traditional format that uses only numbers, the new CNPJ can contain both letters (A-Z) and numbers (0-9) in the first 12 positions.

This change was motivated by the potential exhaustion of available numeric combinations in the current format. By including letters, the number of possible combinations grows from a few million to nearly one trillion unique identifiers, ensuring the long-term sustainability of the system.

The last two digits (positions 13 and 14) remain exclusively numeric, as they are the check digits calculated by the modulo 11 algorithm adapted for alphanumeric characters.

The new alphanumeric CNPJ format is scheduled to take effect from July 2026, as established by Normative Instruction RFB No. 2,229, published in October 2024. Implementation will be gradual, starting with large enterprises.

It is important to note that all existing CNPJs in the traditional numeric format will remain permanently valid. There will be no migration or conversion of current registrations — both formats will coexist indefinitely in the Federal Revenue system.

Companies and developers should prepare their systems to accept the new format by updating form validations and integrations that assume the CNPJ consists only of numbers.

The main motivation for the change is the risk of exhausting available combinations in the current numeric format. With 14 numeric digits (2 being check digits), the number of possible unique CNPJs is limited to approximately 100 million combinations.

Considering that Brazil already has over 58 million registered CNPJs (including inactive ones), and new companies are opened daily, the exhaustion of numeric combinations would become a problem in the medium term.

By including letters (A-Z) in the first 12 positions, the combination space grows exponentially to nearly one trillion possible identifiers, eliminating any risk of exhaustion in the foreseeable future.

The main difference is in the allowed characters: the traditional CNPJ uses only digits (0-9), while the alphanumeric format accepts uppercase letters (A-Z) and digits (0-9) in positions 1 to 12. In both formats, the last two characters (check digits) are always numeric.

The display format remains the same: XX.XXX.XXX/XXXX-XX, with dots, slash and hyphen in the same positions. The only visual difference is that some positions may contain letters instead of numbers.

The validation algorithm is also essentially the same (modulo 11), but with an adaptation: letters receive specific numeric values for calculation. The letter A equals 17, B equals 18, and so on up to Z which equals 42. Numbers keep their face value (0-9).

The calculation uses the same modulo 11 algorithm as the traditional CNPJ, with the difference that letters are converted to numeric values before multiplication by the weights. The conversion follows the rule: A=17, B=18, C=19, ..., Z=42. Digits keep their normal value (0=0, 1=1, ..., 9=9).

For the first check digit, each of the first 12 characters has its value multiplied by the weight sequence [5, 4, 3, 2, 9, 8, 7, 6, 5, 4, 3, 2]. The sum of products is divided by 11 — if the remainder is less than 2, the digit is 0; otherwise, it is 11 minus the remainder.

The second digit is calculated including the first check digit, using the weights [6, 5, 4, 3, 2, 9, 8, 7, 6, 5, 4, 3, 2]. This approach ensures backward compatibility with traditional CNPJs, since digits retain their original values.