What 3001 and 3003 actually mean
If you live in Bern, you see numbers like 3001 and 3003 all the time on official letters and company addresses. Yet, if you try to look them up in a standard demographic directory, they seem to be missing.
That is because they aren't standalone, physical neighborhoods like 3004 Bern or 3011 Bern. They are organizational routing codes. 3001, for example, is primarily used for P.O. boxes (Postfächer). 3003 is the dedicated postcode for the Swiss federal administration (Bundesverwaltung).
You can mail a letter to 3003, but you can't rent an apartment there. Since nobody has their permanent residential address in 3003, there are no tax multipliers, demographic stats, or municipal boundaries attached to it in the same way as a normal postcode.
How to make sense of the data
If you are trying to analyze data on PLZHub, you have to separate domiciliary postcodes (where people live) from administrative or routing postcodes (how mail gets sorted).
A standard residential postcode will have a clear swisstopo locality scope, meaning it covers a physical polygon on a map. Routing codes do not. If you are trying to find tax rates for a company located at a 3001 address, you actually need to find the physical postcode of their building to get the right municipality data.
When the official source has to decide
PLZHub helps you quickly identify whether a postcode is a real neighborhood or just a sorting mechanism. But once you need to officially register a company or calculate taxes, the official cantonal or federal registers have the final say. They will always map the administrative P.O. box back to a physical street address.
