-아/어야 하지 않을까요?
tentatively suggest what should be done
Form
The visible annotation is 을까요, but it belongs to 않을까요? inside the full construction V-아/어야 하지 않을까요? — “shouldn’t we V?”
Function
The speaker presents an action as probably necessary while leaving the other person room to agree or disagree. 찾아봐야 하지 않을까요? therefore means “Shouldn’t we look for them?” rather than giving an order.
Why this form?
-아/어야 해요 — “must / need to…”: directly states necessity without opening it to discussion.
-아/어야 할까요? — “do we need to / should we…?”: more openly asks what the correct obligation or decision is.
-아/어야 하지 않을까요? — “shouldn’t we…?”: the speaker already leans toward that solution and gently seeks the other person’s agreement.
How to build it
V-아/어야 하다 “have to” + -지 않다 “not” + -(으)ㄹ까요? question/suggestion → -아/어야 하지 않을까요?. The negative is rhetorical: it softens the suggestion rather than denying the necessity.
Forms not to confuse
-아/어야 해요
지금 출발해야 해요. — We need to leave now.
-아/어야 할까요?
지금 출발해야 할까요? — Should we leave now?
Examples
그 사람들을 찾아봐야 하지 않을까요? — Shouldn’t we look for those people?
먼저 경찰에 연락해야 하지 않을까요? — Shouldn’t we contact the police first?