You talk about changing host families if you end your stay as an au pair in one host family and move in with another host family. Au pairs mostly change families if they want to stay longer in the country but their au pair stay with the host family is already over.
Sometimes it can happen that living with your host family just doesn’t work out. You don’t feel well in the host family as an au pair and even talking to your host family can’t solve the problems.
Then the only thing that can help is changing families. In this case you end your au pair stay in your current host family early.
Here you can find a checklist if you want to change families, so you won’t forget anything.
If you want to change families you should talk to your current host family about it and let them know in advance so you have enough time to find a new family and they also have time to adapt to the new situation. That’s the fairest way for both sides.
The term of notice for you as an au pair is usually 2 weeks.
If you came with a visa into the country as an au pair you should go together with your host family to the immigration office to make sure you can stay in the country legally.