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OIB Generator (Croatia Tax ID / Personal ID)

Generate and format valid Croatian OIB numbers for software development and QA testing.

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About Croatian OIB (Osobni Identifikacijski Broj)

The OIB (Osobni Identifikacijski Broj) is the unified permanent personal identification and tax number for individuals and corporations in Croatia, managed by the Tax Administration (Porezna uprava) of the Ministry of Finance.

Composed of exactly 11 decimal digits, where the first 10 digits form the base sequence and the 11th digit is a checksum strictly calculated according to ISO 7064 Module 11, 10.

Check Digit Calculation Algorithm (ISO 7064 Mod 11, 10)

  1. Initialize accumulator variable a = 10.
  2. For each of the first 10 digits d[i]: calculate a = (a + d[i]) % 10. If a equals 0, reset a = 10. Then calculate a = (a × 2) % 11.
  3. Compute check value: Control = 11 - a.
  4. If Control is 10, check digit is 0; otherwise, check digit equals Control.

Frequently Asked Questions & Technical Guidelines