Home CUIT / CUIL Argentina
Argentina CUIT / CUIL validator
How the CUIT / CUIL format works
- Format
- 11 digits: 2-digit type prefix + 8-digit body + 1 check digit (XX-XXXXXXXX-X)
- Example
- 20123456786
Things to watch for
- The first 2 digits are a type prefix — 20/23/24/27 identify individuals (CUIL), 30/33/34 identify companies and other entities
- Format + weighted mod-11 check digit only — a pass doesn't confirm the CUIT/CUIL is currently active or registered with AFIP
- A CUIL identifies a specific individual — this check runs entirely in your browser, so nothing you type is stored or transmitted
^[0-9]{11}$A CUIT (Clave Única de Identificación Tributaria) or CUIL (Código Único de Identificación Laboral) is the 11-digit number Argentina’s tax authority, AFIP, uses to identify taxpayers — for example 20-12345678-6. Both names cover the same 11-digit structure: CUIL identifies individuals, CUIT identifies companies and other registered entities, and for someone who becomes self-employed or starts a business, the number is typically relabeled rather than reissued.
The first 2 digits are a type prefix that says which one you’re looking at: 20, 23, 24, and 27 identify individuals (CUIL), while 30, 33, and 34 identify companies and other entities (CUIT). The next 8 digits are the body — for an individual, this is usually their DNI (Documento Nacional de Identidad) number — and the final digit is a check digit produced by a weighted mod-11 calculation over the first 10 digits. Because that last digit is derived rather than arbitrary, a single mistyped digit almost always breaks the checksum instead of quietly pointing to a different valid number.
How this validator works
This tool checks that the input is 11 digits and runs the real weighted mod-11 formula AFIP uses to generate a CUIT/CUIL’s check digit, entirely in your browser. A calculation that lands on the raw value 10 is rejected outright, since it has no corresponding check digit. Nothing is sent to a server, and there’s no signup.
What a pass doesn’t tell you
A pass confirms the number is a mathematically valid CUIT/CUIL — not that it’s currently active with AFIP, or that the individual or company it identifies still holds that status. Because the body often embeds a real DNI, treat any CUIT/CUIL you handle as potentially identifying, the same as you would a standalone ID number.
Scope: this page and tool cover CUIT/CUIL format and checksum validation only — not AFIP registration status or identity verification.
Content last reviewed 2026-07-23.
CUIT / CUIL FAQ
What's the difference between a CUIT and a CUIL?
They're issued by the same agency, AFIP, and follow the same 11-digit format and check-digit formula — the difference is who holds it. A CUIL (Código Único de Identificación Laboral) identifies an individual, typically starting with 20, 23, 24, or 27, while a CUIT (Clave Única de Identificación Tributaria) starting with 30, 33, or 34 identifies a company or an individual registered as a business taxpayer.
Does a CUIT actually contain my DNI number?
For most individuals, yes — the 8-digit body between the type prefix and the check digit is usually the person's DNI (Documento Nacional de Identidad) number. That's one reason a CUIT/CUIL should be handled with the same care as any other personal ID number.
Does a valid checksum mean the CUIT is registered with AFIP?
No. This tool only confirms the 11 digits pass the weighted mod-11 calculation AFIP uses to generate a valid CUIT/CUIL — it doesn't confirm the number was ever issued, or that the person or company's registration is currently active.