Validating Peru RUC Numbers in Python

Peru company tax numbers (RUC) are 11 digits. The last digit is a checksum. Here is how to validate one in Python, and how to check it against the official SUNAT registry.

First, the checksum:

def ruc_checksum_ok(ruc: str) -> bool: if len(ruc) != 11 or not ruc.isdigit(): return False weights = [5, 4, 3, 2, 7, 6, 5, 4, 3, 2] total = sum(int(d) * w for d, w in zip(ruc[:10], weights)) remainder = total % 11 check = 11 - remainder if check == 10: check = 0 elif check == 11: check = 1 return check == int(ruc[10]) 

This catches typos, but it does not tell you if the company exists. For that, check against SUNAT data. ValidaRUC is a free API that does this:

from validaruc import ValidaRUC client = ValidaRUC("your-api-key") result = client.validate("20100070970") print(result.nombre) print(result.estado) 

Get a free key at https://rapidapi.com/MohsinIshaq/api/validaruc — 100 requests per month, no card needed.

The API returns the company name, status, address, and more, straight from the SUNAT Padron Reducido.