〜ずには済まない・〜ないでは済まない
can't get away without, will have to
Verb ない-stem + ずには済まない (する → せずには済まない)
Sign up free to review this point on a spaced schedule.
ずには済まない means that, given the situation or social rules, you can't avoid doing something: 人に迷惑をかけたのだから、謝らずには済まない, "you caused trouble, so you'll have to apologise".
The verb is usually an obligation you'd rather avoid: apologising, reporting, paying for damage, explaining or taking responsibility. The pressure comes from the situation, not from your own feelings.
It's the exact opposite of ずに済む (N2), "get away without doing": 謝らずに済んだ, "I got away without apologising". ないでは済まない means the same.
Compare ずにはおかない, which is about something being bound to happen, or someone's strong resolve.
Examples
人に迷惑をかけたのだから、謝らずには済まない。
You caused trouble, so you'll have to apologise.
このミスは、部長に報告せずには済まないだろう。
We'll have to report this mistake to the department head.
高い花瓶を割ってしまった。弁償せずには済まない。
I broke an expensive vase. I'll have to pay for it.
これだけの問題になれば、社長が説明せずには済まない。
Now that it's become such a big problem, the president will have to explain.
約束を破ったのだから、責任を取らずには済まない。
You broke your promise, so you'll have to take responsibility.