〜ずに（ないで・なくて・なしで）済む

About

A combination of a verb ending with either ～ずに, ～なくて, or ～ないで and 「済すむ」 ("to be resolved"), ～ずに済すむ is used to express that one avoided having to do X undesirable action. It is often used in contexts where the speaker had been worried and now feels relieved at not having to do said action.

The verb 済すむ can mean many different things, from "to be finished" to "to be completed" or "to be resolved", and it carries these nuances with it in the ～ずに済すむ pattern.

～ずに済すむ is most commonly used in casual/polite spoken scenarios.

～なくて済すむ・ないで済すむ and ～ずに済すむ are all possible, and are essentially interchangeable. (～ずに済すむ is slightly more polite/formal/written in tone than the others, as ～ずに is a more formal structure.)

For nouns, なしで済すむ is used instead.

E.g. マツエクをしたから、毎日まいにちマスカラをしなくて済すむ。 "I got eyelash extensions, so I can get away without doing my mascara every day."

E.g. 保険ほけんが効きくから、半額はんがく払はらわなくて済すんだ。 "Insurance covered it so I got away without paying half (of the cost)."

E.g. 誰だれも見みてなかったのでバレずに済すんだ。 "No one was watching, so I got away without being found out."

Summary

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  The ～ずに・なくて・ないで済すむ pattern is used to express that one avoided having to do X undesirable action

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  ～ずに・なく・ないで may be used interchangeably in combination with 済すむ

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  ～ずに済すむ is most commonly used in casual/polite spoken scenarios