[jack_tripper]

Can't concur. As a kid I learned foreign languages effortlessly, compared to now as an expat. And every other expat here my age shares the same experiences, where their 8 year old already speak the host country's language better than they do.

[somenameforme]

As another expat, I'd concur with him, with an asterisk. The thing is - your kids are surrounded by the language nonstop. Depending on your situation it may be spoken at school, certainly spoken by some of their friends, teachers, and so on endlessly. But "you" (speaking in generalities of expats and not necessarily literally you)? Unless you happen to have a local wife, then you probably speak it extremely rarely, there's a reasonable chance you can't even read it if it's non-latin, and there's no real need to move beyond that.

Living in one country for a rather long time, my fluency was basically non-existent beyond simple greetings, shopping/eating, and other basic necessities. By contrast somewhat recently I've taken a major interest in another language, one that's generally considered extremely difficult, and I've reached at least basic fluency in about 3 years. The difference? I immersed myself in the other language, my music playlist is overwhelmingly in that language, I've watched endless series and movies in that language, I've made efforts to read books in the other language, and any time I find another speaker I make sure to use the opportunity to talk with him in that language, and so on. If I was in a country where it was the native language, then I'd probably be near fluent by now.