Is it sometimes considered politer or more formal to say ちゃう・じゃう as opposed to してしまう? Does it give a more positive nuance than してしまう?

An example: One time I was going to be late to a dinner date and someone called me asking how late I would be. They were nervous and I'm their senior so they were using keigo the whole time, and then I said something like "it's ok if you start without me," and they replied 「それでは、はじまっちゃいます」 which I took to mean "ok, we're going to go ahead and start then."

I mean its not a big deal to me but I was just curious because intuitively it does feel like saying 「それでは、はじまってしまいます」would be completely wrong. Something about てしまう gives me more of a nuance of agency where ちゃう and じゃう don't.

  • 2
    Talking about ちゃ and じゃ here is kind of like talking about the formality of gon and wan rather than gonna and wanna.
    – user1478
    Mar 14, 2017 at 5:06

1 Answer 1


I think they actually said 始めちゃいます using 始る (transitive).

~ちゃう is always colloquial and relatively informal, but usually not impolite. It's inappropriate to use ~ちゃう in formal greetings and business letters. But in everyday conversations, many people use it even when they are talking with their bosses using light keigo (です/ます). If you were an unfriendly 怖い上司, they might have avoided ~ちゃう and said それでは始めてしまいます.

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