| Place | Post Code |
|---|---|
| Allanooka, Irwin | 6525 |
| Arrowsmith, Irwin | 6525 |
| Bonniefield, Irwin | 6525 |
| Bookara, Irwin | 6525 |
| Dongara, Irwin | 6525 |
| Irwin, Irwin | 6525 |
| Milo, Irwin | 6525 |
| Mount Adams, Irwin | 6525 |
| Mount Horner, Irwin | 6525 |
| Port Denison, Irwin | 6525 |
| Springfield, Irwin | 6525 |
| Yardarino, Irwin | 6525 |