formality of ちゃう・じゃう


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.




I think they actually said 始めちゃいます using 始 **め** 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.




I think they actually said 始めちゃいます using 始 **め** 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.

