Don't Have To / Must Not

Express lack of necessity or prohibition: -지 않아도 되다 - "don't have to" / "don't need to" • V stem + 지 않아도 되다 • 가지 않아도 돼요 = You don't have to go • 걱정하지 않아도 돼요 = You don't have to worry • Also: 안 -아/어도 돼요 -(으)면 안 되다 - "must not" / "shouldn't" • V stem + (으)면 안 되다 • 여기서 담배 피우면 안 돼요 = You must not smoke here • 늦으면 안 돼요 = You must not be late Key difference: • 안 해도 돼요 = You don't have to (optional) • 하면 안 돼요 = You must not (prohibited)