Obligation and necessity

아/어야 해요 is the main Korean pattern for saying “have to” or “must”. It is used when an action is necessary because of a rule, schedule, responsibility, health condition, or personal situation.

The structure is Verb stem + 아/어야 해요. If the verb naturally takes 아, use 아야 해요; if it takes 어, use 어야 해요; and with 하다 verbs, use 해야 해요.

For example, 가다 becomes 가야 해요, meaning “have to go”. 먹다 becomes 먹어야 해요, meaning “have to eat”. 공부하다 becomes 공부해야 해요, meaning “have to study”.

This pattern is extremely common in real Korean. You can use it for daily duties: 일해야 해요 — “I have to work”, 병원에 가야 해요 — “I have to go to the hospital”, and 약을 먹어야 해요 — “I have to take medicine.”

Many useful Korean verbs end in 하다: 공부하다 to study, 일하다 to work, 운동하다 to exercise, 전화하다 to call, 청소하다 to clean, and 준비하다 to prepare.

With these verbs, the obligation form is very regular: 하다 becomes 해야 해요. So 공부하다 becomes 공부해야 해요, 운동하다 becomes 운동해야 해요, and 준비하다 becomes 준비해야 해요.

This is one of the easiest obligation patterns to use because you do not need to think much about vowel harmony. Once you know the noun part, attach 해야 해요.

In daily life, this pattern is everywhere. Students say 공부해야 해요, workers say 일해야 해요, parents say 청소해야 해요, and patients may say 운동해야 해요 if the doctor tells them to exercise.

아/어야 돼요 also means “have to” or “must”. In daily Korean, both 아/어야 해요 and 아/어야 돼요 are common. Their meaning is very close.

해야 해요 can feel slightly more like “I have to do it / it is required”. 해야 돼요 can feel slightly more like “it has to be done / it needs to happen”. But in beginner Korean, you can treat them as almost the same.

For example, 가야 해요 and 가야 돼요 both mean “I have to go.” 먹어야 해요 and 먹어야 돼요 both mean “I have to eat.”

You will hear 돼요 very often in real conversation. It is the same 돼요 you learned in permission patterns like 가도 돼요?, but here it appears after 아/어야 to express necessity.

To say that something is not necessary, Korean often uses 안 해도 돼요, meaning “you do not have to do it” or “it is okay even if you do not do it”.

The general idea is 안 + Verb아/어도 돼요: even if you do not do it, it is okay. For 하다 verbs, the natural form is often 안 해도 돼요 after the noun part: 공부 안 해도 돼요, 운동 안 해도 돼요, 걱정 안 해도 돼요.

This pattern is different from 하면 안 돼요. 하면 안 돼요 means “you must not do it”. 안 해도 돼요 means “you do not need to do it”. One is prohibition; the other is lack of necessity.

This distinction is very important. 먹으면 안 돼요 means “You must not eat.” 안 먹어도 돼요 means “You do not have to eat.”

To ask whether something is necessary, use the same obligation pattern with question intonation: 해야 해요?, 가야 해요?, 먹어야 해요?.

For example, 지금 가야 해요? means “Do I have to go now?” 이걸 해야 해요? means “Do I have to do this?” 약을 먹어야 해요? means “Do I have to take medicine?”

A useful answer is 네, 해야 해요, meaning “Yes, you have to.” The negative answer is 아니요, 안 해도 돼요, meaning “No, you do not have to.”

This pair is very practical in schools, hospitals, workplaces, and public offices. It lets you ask clearly whether something is required, and it lets the other person answer whether it is necessary or optional.