How does the tool know which algorithm to use?

The 3rd digit decides. Values 0-5 mark a natural person validated with Module 10, a value of 9 marks a private company validated with Module 11 over 9 digits, and a value of 6 marks a public entity validated with Module 11 over 8 digits. Each has a different establishment suffix too.

What is the establishment suffix?

The last digits identify the establishment. Natural persons and private companies end in 001, while public entities end in 0001. The validator checks the suffix matches the entity type as well as the check digit.

Why is the province code checked?

The first two digits are the province of issue and must be between 01 and 24, or 30 for Ecuadorians registered while resident abroad. An out-of-range province is an immediate sign of an invalid number.

Is my RUC sent anywhere?

No. Type detection, the check-digit maths, and suffix validation all run in your browser. Nothing is uploaded, so it is safe to validate supplier and customer lists.

Ecuador RUC Validator

Q: Does a valid RUC mean the taxpayer is registered?

No. A valid result means the RUC is internally consistent under the SRI check-digit rules. It does not confirm the taxpayer is registered or active. Confirm status on the official SRI portal before issuing electronic invoices.

The RUC (Registro Único de Contribuyentes) is Ecuador’s 13-digit tax identifier issued by the SRI. Unlike a single fixed algorithm, the RUC uses three different check-digit rules depending on who holds it, so a correct validator must first work out the entity type. This free tool does exactly that and runs the right algorithm for natural persons, private companies, and public entities.

How it works

Every RUC is a 10-digit base plus an establishment suffix. The 3rd digit selects the entity type and the algorithm:

3rd digit 0-5 — natural person. The base is a 10-digit cédula. A Luhn-style Module 10 runs over the first 9 digits with coefficients 2,1,2,1,2,1,2,1,2 (products over 9 have 9 subtracted); the 10th digit is the check. Suffix 001.
3rd digit 9 — private company. Module 11 over the first 9 digits with coefficients 4,3,2,7,6,5,4,3,2; the 10th digit is the check. Suffix 001.
3rd digit 6 — public entity. Module 11 over the first 8 digits with coefficients 3,2,7,6,5,4,3,2; the 9th digit is the check. Suffix 0001.

The province (first two digits) must be 01-24, or 30 for citizens registered abroad. The tool reports the type, province, expected check digit, and suffix correctness.

Example and notes

A natural-person RUC like 1710034065001 has 3rd digit 1, so Module 10 runs over the first 9 digits. The computed check digit is compared to the 10th, and the suffix 001 is verified.

A valid result confirms internal consistency under the SRI rules — it does not confirm the taxpayer is registered or active. For e-invoicing (comprobantes electrónicos), always confirm the taxpayer status on the SRI portal. Everything runs locally; your RUC never leaves your device.