Argentina CUIT/CUIL Validator
ValidatorValidate an Argentina CUIT/CUIL number instantly and see its type prefix decoded. Confirms the mod-11 check digit with the official substitution rule. Free, runs in your browser.
About this tool
About Argentina CUIT/CUIL Validator
CUIT and CUIL are the same 11-digit number format — Argentina's tax and labor identifier — distinguished only by which 2-digit type prefix is used (20/23/24/27 for individuals, 30/33/34 for companies, plus 50/51/55 for international purposes). The check digit uses weights 5, 4, 3, 2, 7, 6, 5, 4, 3, 2 with a mod-11 sum and a fixed digit-substitution table.
Paste a CUIT/CUIL and the tool verifies the type prefix is one of the recognized values, decodes whether it's an individual or company number, and confirms the check digit against the official substitution table (where a raw mod-11 result of 1 becomes check digit 9, and 0 stays 0).
Use this to verify a client's or supplier's CUIT/CUIL before invoicing in Argentina, or to debug a validation library implementing the substitution rule correctly.
Instant, fully client-side validation with the officially documented digit-substitution table implemented exactly as python-stdnum's reference implementation defines it — not a guessed or gender-based rule.
Key Features
- Verifies the mod-11 check digit with the official substitution table
- Decodes the type prefix as individual, company, or international
- 100% browser-based, no data sent
FAQ
Argentina CUIT/CUIL Validator — Frequently Asked Questions
What does the check-digit substitution rule actually do?
After computing the weighted sum mod 11, most results (2 through 10) map directly to check digit 11-minus-that-result. But a result of 0 maps to check digit 0, and — this is the detail sources often get wrong — a result of 1 maps to check digit 9, not to an "invalid" case. This is a fixed numeric substitution, not something that depends on whether the CUIT/CUIL is for an individual or a company.
Does that mean every 10-digit base has a valid CUIT/CUIL?
Yes. Because of that substitution rule, there's no "no valid check digit exists" case for CUIT/CUIL the way there is for some other tax IDs on this site (like Polish NIP) — every base produces exactly one valid check digit.
What do the different type prefixes mean?
20, 23, 24, and 27 are used for individuals (CUIL); 30, 33, and 34 for companies (CUIT); 50, 51, and 55 are reserved for international purposes. The prefix doesn't affect the checksum calculation at all.
Can this tool confirm a CUIT/CUIL belongs to a real, registered taxpayer?
No. This is a mathematical checksum check only. Confirming registration status requires access to AFIP's (Argentina's tax authority) own systems, which this site cannot query.
Tips
- Spaces and hyphens are stripped automatically before validation
- Use the CUIT/CUIL Generator on this site to create valid test numbers
- RUT (Chile), CPF (Brazil), and CURP (Mexico) are this site's other Latin American national ID tools
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