Australia CRN Validator
Online validator for Customer Reference Number (CRN - Centrelink) issued by Services Australia.
How does Australian CRN validation work?
The validator verifies the 9-digit base number followed by 1 uppercase control letter and calculates the Modulo 11 check letter.
Validation is performed locally in your browser without transmitting any personal data over the internet.
Anatomy & Structure of CRN (Customer Reference Number)
The Centrelink Customer Reference Number consists of 9 digits and 1 check letter:
| Position | Field | Length | Meaning & Rule | Example |
|---|---|---|---|---|
| 1 to 9 | Base Registration Number | 9 digits | Individual welfare and social services registration number | 123456789 |
| 10 | Check Letter | 1 letter | Checksum letter calculated via weighted Modulo 11 and mapped to alphabet | A |
Official CRN Algorithm (Services Australia Modulo 11)
Check letter calculation for Centrelink CRN:
S = Σ d[i] * (10 - i) (i=0..8); R = S mod 11; Letter = alphabet[R]
- 1. Multiply the 9 digits by decreasing weights from 10 to 2.
- 2. Sum all products into total S.
- 3. Compute remainder R = S mod 11.
- 4. Map remainder to corresponding alphabetic check letter.
- 5. CRN is valid if 10th character matches the calculated letter.