日本語道場 — Nihongo Dojo

～次第

~shidai

as soon as; depending on

When to use it

Use ～次第 in the masu-stem pattern when reporting that you will act the moment something happens — it is the written/business-formal counterpart of ～たらすぐに, standard in email (ご連絡します／お知らせいたします). With a noun it means the outcome hinges on that factor, common in negotiation and hedged reporting. Both uses are stiff in casual speech; in conversation prefer ～たらすぐ or ～によって決まる.

Formation

Verb: masu-stem + 次第 — 分かり次第、届き次第、決まり次第 (only for future, non-negated events; the main clause is a will/plan, never a past fact)
Noun: noun + 次第だ／次第で／次第では — 相手次第だ、予算次第で、天候次第では
i-adjective / na-adjective: no direct attachment; nominalize instead — 忙しさ次第、状況次第
Note the separate written idiom 〜という次第です／〜次第でして "such are the circumstances", used to close an explanation

Examples

I'll email you as soon as the details are clear.
As soon as their reply arrives, I'll arrange the schedule.
Whether we agree to a discount depends on my manager's call.
Depending on the budget, we could consider adopting it next term.
Someone dropped out suddenly, and so it's fallen to me to visit.