#english_language 

- We use **didn't need to or didn't have to** when we say that it was not [[Must and have (got) to#^53c6a3|necessary]] and it wasn't done
	> I didn't have/need to cook dinner (=I didn't cook dinner)
- We use **need not have** when we say it was not necessary, but still, in fact, was done
	> I needn't have cooked dinner (=I did cook dinner)