| Locality | Post Code |
|---|---|
| Niezijl, Westerkwartier | 9841, 9842 |
| Noordhorn, Westerkwartier | 9804 |
| Noordwijk, Westerkwartier | 9824 |
| Nuis, Westerkwartier | 9364 |
| Oldehove, Westerkwartier | 9883 |
| Oldekerk, Westerkwartier | 9821 |
| Oostwold, Westerkwartier | 9828 |
| Opende, Westerkwartier | 9865 |
| Pieterzijl, Westerkwartier | 9844 |
| Saaksum, Westerkwartier | 9886 |
| Sebaldeburen, Westerkwartier | 9862 |
| Tolbert, Westerkwartier | 9356 |
| Visvliet, Westerkwartier | 9845 |
| Zevenhuizen, Westerkwartier | 9354 |
| Zuidhorn, Westerkwartier | 9801 |
| Groningen Postal Codes | |
|---|---|
| Westerwolde | Westerkwartier |
| Veendam | Stadskanaal |
| Pekela | Oldambt |
| Midden-Groningen | Loppersum |
| Het Hogeland | Groningen |
| Delfzijl | Appingedam |