The CUIT/CUIL Validator checks whether an Argentine 11-digit number has the correct check digit, applying the modulo-11 algorithm used by AFIP — now succeeded by ARCA.
What it is
The last of the 11 digits in a CUIT/CUIL isn't free: it results from a calculation over the previous 10 digits (2 prefix + 8 number digits). A single changed digit already breaks that calculation, and that's what this tool detects.
Note: this validation is purely mathematical. It does not query AFIP/ARCA or ANSES, so it can't confirm whether the number really exists or who it belongs to.
Who it's for
- Developers and QA validating Argentine customer or employee registrations.
- HR and finance teams checking a CUIT/CUIL before issuing a document.
How the calculation works
The tool multiplies the first 10 digits by the weights 5, 4, 3, 2, 7, 6, 5, 4, 3, 2, sums everything, and takes the remainder of dividing by 11. The expected digit is 11 minus that remainder (or 0, if the result is 11). If it matches the typed 11th digit, the number is valid.
How to use it
Paste the CUIT or CUIL (with or without dashes) and click Validate. To generate valid test numbers, use the CUIT/CUIL Generator.
Worked example
Paste 20-12345678-6 into the field above. The tool strips the dashes, isolates the first 10 digits (prefix + number), applies the weights 5,4,3,2,7,6,5,4,3,2, sums everything, and takes the remainder of dividing by 11. Since the calculation gives 6, and the typed 6 matches, the tool confirms "Valid CUIT/CUIL".