ことになる details
write + it has been decided that
kaku koto ni naru
it has been decided that; it turns out that
来月、大阪に転勤することになりました。
raigetsu, oosaka ni tenkin suru koto ni narimashita.
It's been decided that I'll transfer to Osaka next month. neutral
日本では、家の中では靴を脱ぐことになっています。
nihon de wa, ie no naka de wa kutsu o nugu koto ni natte imasu.
In Japan, the custom is that you take your shoes off inside the house. neutral
- decision announced
- polite past
- standing arrangement
Examples
it has been decided that — an outcome presented as settled by others or by circumstance
来月、大阪に転勤することになりました。
raigetsu, oosaka ni tenkin suru koto ni narimashita.
It's been decided that I'll transfer to Osaka next month. neutral
実は、うち、引っ越すことになったんだ。
jitsu wa, uchi, hikkosu koto ni natta n da.
Actually, it turns out we're moving. casual
it is the rule that — standing arrangements and customs with ことになっている
日本では、家の中では靴を脱ぐことになっています。
nihon de wa, ie no naka de wa kutsu o nugu koto ni natte imasu.
In Japan, the custom is that you take your shoes off inside the house. neutral
会議室の使用後は、施錠することになっております。
kaigishitsu no shiyougo wa, sejou suru koto ni natte orimasu.
The rule is that the meeting room is to be locked after use. formal
Formation
{V}ことになるattaches to dictionary form{V-nai}ことになるattaches to ない-form
Notes
Related patterns
Similar
になる states a bare change of state (春になる); ことになる wraps a whole event as an arranged outcome — 転勤することになった says somebody decided it, while 春になった claims nothing about anyone's hand in the change.
Both report arrangements the speaker does not claim to have willed — 予定だ cites a calendar entry, ことになった cites a decision handed down; only ことになる also carries the "it turned out that" reading.
Lookalikes
One verb apart — する means the subject made the choice, なる reports it as settled elsewhere; even self-chosen job moves get announced as ことになりました to mute the self-assertion.