Expressing Lack of Obligation, with
You don't have to / need to ～
Forming the Stucture:
To form the first half (the ～なくても bit):
- Begin with a verb in the plain form negative.
E.g. しない (I don't do); やらない (I don't do); 行かない (I don't go)
- Remove the final ない and replace with なくても
- So, しない becomes しなくても (even if you don't do);
やらない becomes やらなくても (even if you don't do);
行かない becomes 行かなくても (even if you don't go).
To form the second half (the いいです bit):
- Simply add いいです, which means "it's OK"/"it's fine"/"it's (all) good"
- Essentially, you're saying "Even if you don't do (A), it's fine", so in other words, "You don't have to do (A)".
- Which gives you:
しなくてもいいです・やらなくてもいいです (both mean "You don't have to do");
行かなくてもいいです ("You don't have to go")
Some more examples: