Turkey Vergi Kimlik No Validator

The Vergi Kimlik No (VKN) is the 10-digit taxpayer number Turkey’s Gelir İdaresi Başkanlığı (GİB) issues to companies and organisations. It is required on Turkish tax invoices, e-Arşiv documents, and GİB filings. The VKN carries one self-check digit, so transcription errors can be caught immediately. This validator runs the official algorithm in your browser.

How it works

The 10th digit is a check digit derived from the first 9 digits with a digit-shuffle and power-of-two scheme:

1. Strip non-digits. The number must be exactly 10 digits.
2. For each of the first 9 digits at 1-based position i (i from 1 to 9):
   • tmp = (digit + (10 − i)) mod 10.
   • If tmp is 0, the contribution is 0.
   • Otherwise compute (tmp × 2^(10−i)) mod 9. If that result is 0, the contribution is 9; otherwise it is that result.
3. Sum the 9 contributions.
4. The 10th digit equals (10 − (sum mod 10)) mod 10.
5. The VKN is valid when the computed 10th digit equals the actual 10th digit.

Example

For a VKN, position 1 uses weight 2^9 = 512, position 2 uses 2^8 = 256, and so on down to position 9 using 2^1 = 2. Each weighted, shuffled digit is reduced modulo 9 before summing. The tool shows the running sum and the resulting expected check digit so you can confirm the final digit by hand.

Notes

A valid check digit confirms the VKN is consistent, not that the taxpayer is registered or active — use official GİB services for that. Everything runs locally, so your VKN never leaves your device.