Söderup was formerly part of the German Empire. In the German Empire, the place was called Söderup.
The place is now called Søderup and belongs to Denmark.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Söderup | German Empire | Apenrade | before the Versailles Treaty |
| Søderup | Denmark | Aabenraa | after the Versailles Treaty |
| Søderup | Denmark | Sønderjylland | 1993 |