Polish REGON Business Register Validator
Validate structural compliance and check digits of Polish REGON numbers (9 or 14 digits).
About Polish REGON Validation
Validation checks 9 or 14 digits and computes the weighted Modulo 11 security digit.
Supports both corporate headquarters and local business units/branches.
Anatomy & Structure of Polish REGON
REGON consists of 9 digits (principal entity) or 14 digits (local unit):
| Position | Field | Length | Meaning & Rule | Example |
|---|---|---|---|---|
| 1 to 2 | Voivodeship Code | 2 digits | Statistical identifier of the Polish province | 12 |
| 3 to 8 | Entity Base | 6 digits | Sequential company number assigned by GUS | 345678 |
| 9 | Check Digit (9d) | 1 digit | Modulo 11 check digit for headquarters | 5 |
| 10 to 13 | Branch Sequence | 4 digits | Local unit identifier (14-digit REGON only) | 1234 |
| 14 | Check Digit (14d) | 1 digit | Modulo 11 check digit for the local unit | 7 |
REGON Calculation & Validation Algorithm (Modulo 11)
REGON validation applies positional weights with Modulo 11:
DV = (∑ di × Weights[i]) mod 11 (if remainder = 10, DV = 0)
- 1. Remove spaces and non-digit characters.
- 2. Validate that the sequence has 9 or 14 digits.
- 3. For 9 digits: multiply by weights [8, 9, 2, 3, 4, 5, 6, 7] and calculate remainder by 11.
- 4. For 14 digits: multiply 13 digits by [2, 4, 8, 5, 0, 9, 7, 3, 6, 1, 2, 4, 8] and calculate remainder by 11.
- 5. If the remainder is 10, set the expected check digit to 0.
- 6. Compare the obtained value against the final check digit.