[rhblake]

On the other hand it's trivial to change someone's official address. Just send a certain form by mail to the tax agency. (Not sure if they send a confirmation to the old address; but if they do, the perpetrator only has to pick someone who's on vacation; hello Twitter & Facebook.)

[petriw]

If you have registered an email / phone number they will send a message there about your changed address.

I don't know if they've done this yet but a while ago there were articles about them working on a way to disallow changing your address via the mail form:

http://www.dn.se/ekonomi/sa-ska-id-kapningar-forhindras/