REGON validator - check a Polish business REGON number

REGON is the identification number in the Polish National Official Business Register, maintained by the President of Statistics Poland (GUS). Companies, sole traders, foundations, associations and public bodies all have one. It is assigned automatically when a business registers in CEIDG (sole traders) or KRS (companies), so there is no separate application.

• 9-digit REGON - identifies an entity, such as a limited company or a self-employed person,
• 14-digit REGON - identifies a local unit, such as a branch or plant; it consists of the 9-digit entity REGON, a 4-digit local unit number and a check digit.

9-digit REGON: multiply the first 8 digits by the weights 8, 9, 2, 3, 4, 5, 6, 7, add the results and divide by 11. The remainder is the check digit; if it is 10, the check digit is 0.

Example: 123456785 gives 1·8 + 2·9 + 3·2 + 4·3 + 5·4 + 6·5 + 7·6 + 8·7 = 192, and 192 mod 11 = 5, which matches the last digit.

14-digit REGON: multiply the first 13 digits by 2, 4, 8, 5, 0, 9, 7, 3, 6, 1, 2, 4, 8 and continue the same way (mod 11, remainder 10 becomes 0).

Example: 12345678512347 gives a sum of 260, and 260 mod 11 = 7, so the number is valid, and its first 9 digits (123456785) are a valid parent REGON.

You will find a REGON in CEIDG or KRS extracts, in the GUS online search, and often in a company website footer or letterhead. It is requested in grant and loan applications, contracts, public tenders and official forms. It is not required on invoices. Polish VAT rules require the NIP, which you can check with the Polish NIP validator.

Typical errors: giving a 14-digit branch number where the entity REGON is required (the first 9 digits are enough), confusing REGON with NIP (10 digits), and losing a leading zero when a spreadsheet treats the REGON as a number. The validator requires exactly 9 or 14 digits, so a lost zero shows up at once. To check a Polish bank account use the IBAN validator.