～ことになる
it has been decided that
～ことになる is made from the noun こと (thing, matter), the particle に, and なる (to become). It reports a decision or outcome as something that came about, rather than something the speaker chose.
In English it matches expressions like “it has been decided that” or “it turns out that”. Japanese often prefers this wording even when the speaker took part in the decision, because it sounds modest.
1. A decision made by others or by circumstance
Use ～ことになる (usually in the past, ことになりました) to announce an arrangement without presenting it as your own choice.
来月転勤することになりました。
“It has been decided that I will be transferred next month.”
- 来月（らいげつ）= next month
- 転勤する（てんきんする）= to be transferred (to another office)
- ことになりました = it has been decided that
2. A standing rule or arrangement (～ことになっている)
In the ている form, the pattern describes a rule, custom, or arrangement that is currently in force.
ここでは靴を脱ぐことになっています。
“The rule here is that you take off your shoes.”
- ここ = here
- では = place marker で + topic marker は
- 靴（くつ）= shoes
- を = object marker
- 脱ぐ（ぬぐ）= to take off
- ことになっています = it is the rule that
Compare ～ようになる, which describes a gradual change in ability or habit; ～ことになる describes a decision or arrangement. If the speaker makes the decision personally, Japanese uses ～ことにする instead.
How to form it
Verb dictionary form (or ない-form) + ことになる
- 転勤する（てんきんする）= to be transferred → 転勤することになる（てんきんすることになる）= it is decided that ... will be transferred
- 住む（すむ）= to live → 住むことになりました（すむことになりました）= it was decided that ... will live
- 行かない（いかない）= will not go → 行かないことになった（いかないことになった）= it was decided that ... will not go
Key idea
～ことになる presents an outcome as something that became so on its own. The person who decided stays in the background, which makes announcements sound objective and humble.
Built on the same stem
Updated .