We have a letter of invitation which covers the hours they're expected to work during the day, duties, pay, arrangement for language schools, accommodation, vistors, holiday entitlement, notice period, grounds for immediate dismissal, and a description of our family life.
The language is not formal the way our nanny contract is, as for one thing I am not sure how much all the au pairs would understand of that and I wouldn't want them to stop reading! But it covers the areas of interest.
We do this because I want the au pair to be fully informed of what she's taking on before she arrives - we'll have discussed most of it, but I want them to see it in writing and email me back saying, I've read it and I've understood. I just think this is best practice in terms of being fair to the au pair and protecting ourselves.
I have the feeling that some of these girls are so excited to get an offer, they accept immediately and may not have thought it through and really SHOULD be seeing it all again in print.
This doesn't mean they never need to be told again - and I am not sure how enforceable these docs are. I mean - if I had a really unhappy au pair would I hold her to the four wks notice? Probably not. But I think showing that you are starting on a professional basis kind of 'shows how you mean to go on' so to speak.