Validate INN online by checksum — verify individual and company INN. INN structure decoder: region, tax office code, number type.
INN Structure Decoding
INN check digit validation using the official algorithm. Determines type (legal entity/individual) by length. Does not verify existence in the FNS registry.
INN structure: first 2 digits — RF subject code, next 2 — tax office number, then serial number and check digits.
For legal entities (10 digits): NNNN + 5 serial digits + 1 check digit. For individuals (12 digits): NNNN + 6 serial digits + 2 check digits.
INN Validation Online — Checksum Verification and Structure Decoding
This tool verifies INN correctness using the checksum algorithm and decodes the number structure: determining the type (individual or organization), region code, tax office number, and serial number. Results are displayed with color coding for clarity.
Why Validate INN
- Counterparty verification — ensure a partner provided a valid number before signing a contract
- Document preparation — eliminate typos in invoices, contracts, and payment orders
- Form validation — input checking on websites and in accounting systems
- Testing — verifying generated test data
Checksum Validation Algorithm
For 10-digit INN (organizations): the check digit = (weighted sum with weights [2,4,10,3,5,9,4,6,8]) mod 11 mod 10.
For 12-digit INN (individuals): two check digits are computed — the 11th using weights [7,2,4,10,3,5,9,4,6,8] and the 12th using [3,7,2,4,10,3,5,9,4,6,8].
INN Structure Decoding
| Positions | Meaning | Example (INN 7707083893) |
|---|---|---|
| 1–2 | Region code | 77 — Moscow |
| 3–4 | Tax office number | 07 — Tax Office #7, Moscow |
| 5–9 (10-dig.) or 5–10 (12-dig.) | Serial number | 08389 |
| Last 1 (10-dig.) or 2 (12-dig.) | Check digit(s) | 3 |
How to Verify a Counterparty by INN
Beyond checksum validation, check the INN in official sources: the Federal Tax Service "Transparent Business" service, EGRUL/EGRIP registries. This helps confirm the organization is active and has no tax debts.
Frequently Asked Questions
What does "INN failed validation" mean?
The check digit does not match the calculated value. This may indicate a typo, a deliberately fictitious number, or a copy error.
If INN passes validation, is it real?
Not necessarily. Validation confirms mathematical correctness but not registration with the tax service. Use EGRUL for existence verification.
Can I find an organization by INN?
Yes, through the Federal Tax Service (egrul.nalog.ru) you can find the full name, address, activity type, and registration date.
What is the difference between INN and OGRN?
INN is the taxpayer identification number (10 or 12 digits). OGRN is the main state registration number (13 or 15 digits). Check OGRN with the OGRN validator.
To generate test INNs use the INN generator.
Useful articles
OGRN: How to Validate and Decode a Company Registration Number
A breakdown of the OGRN structure, the meaning of each digit group, the check digit verification algorithm, and the differences between OGRN and OGRNIP for sole proprietors.
SNILS: Format, Check Digit, and Test Data
A breakdown of the SNILS format, the check digit algorithm, its role in the social security system, and why developers need test data.