How to Say "Must" and "Have To" in Korean: ~아/어야 해요

There are things you want to do, things you plan to do - and then there are things you have to do.

In Korean, that last category has its own grammar pattern: ~아/어야 해요.

It's one of the most essential A2 patterns - because obligation, necessity, and duty come up in every real conversation. This post covers everything you need to know.

What Does ~아/어야 해요 Mean?

~아/어야 해요 expresses obligation or necessity - something that must be done, has to happen, or is required.

공부해야 해요. I have to study.

지금 가야 해요. I have to go now.

How to Form ~아/어야 해요

Step 1: Remove 다 → get the verb stem Step 2: Apply the same vowel rule as ~아요/어요:

💡 When the stem ends in a vowel ㅏ or ㅗ, 아야 contracts naturally: 가 + 아야 해요 = 가야 해요 (not 가아야 해요)

Conjugation Table

~아/어야 해요 in Real Sentences

📚 Study & Work

오늘 숙제를 끝내야 해요.

• Literal: Today homework [object] finish have to
• Natural: I have to finish my homework today.

이 보고서를 내일까지 보내야 해요.

• Natural: I have to send this report by tomorrow.

회의 전에 자료를 준비해야 해요.

• Natural: I have to prepare the materials before the meeting.

한국어를 더 열심히 공부해야 해요.

• Natural: I have to study Korean harder.

🏃 Daily Life

일찍 일어나야 해요. 비행기가 아침 여섯 시예요.

• Natural: I have to wake up early. The flight is at 6 AM.

오늘 마트에 가야 해요. 냉장고가 비었어요.

• Natural: I have to go to the market today. The fridge is empty.

약을 매일 먹어야 해요.

• Natural: I have to take medicine every day.

지금 출발해야 해요. 늦겠어요.

• Natural: I have to leave now. I'll be late.

💬 Advice & Recommendations

~아/어야 해요 is also used to give advice or recommendations - telling someone what they should or need to do:

한국에 가면 삼겹살을 먹어야 해요.

• Natural: If you go to Korea, you have to eat samgyeopsal.

그 드라마 꼭 봐야 해요. 너무 재미있어요.

• Natural: You absolutely have to watch that drama. It's so good.

감기에 걸리면 푹 쉬어야 해요.

• Natural: If you catch a cold, you have to rest well.

건강하려면 매일 운동해야 해요.

• Natural: To be healthy, you have to exercise every day.

Past Tense: Had To

Replace 해요 with 했어요:

Future Tense: Will Have To

Combine with 할 거예요 or 할 것 같아요:

안 ~아/어야 해요 vs ~지 않아도 돼요

This is where many learners make a mistake. "Don't have to" and "must not" are very different in Korean:

❌ "I don't have to go" is NOT 가야 안 해요. ✅ It's 가지 않아도 돼요. (covered in the next blog!)

Real Conversations Using ~아/어야 해요

📍 Conversation 1: Morning rush

A: 왜 이렇게 빨리 가요? (Why are you leaving so quickly?)

B: 9시까지 회사에 가야 해요. 지금 안 나가면 늦어요. (I have to be at work by 9. If I don't leave now, I'll be late.)

A: 밥은 먹었어요? (Did you eat?)

B: 아니요, 그냥 가야 할 것 같아요. (No, I think I'll just have to go.)

A: 그래도 뭐라도 먹어야 해요! (Still, you have to eat something!)

📍 Conversation 2: Planning a trip

A: 한국 여행 준비 많이 했어요? (Have you prepared a lot for the Korea trip?)

B: 아직요. 비자 신청해야 하고, 숙소도 예약해야 해요. (Not yet. I have to apply for a visa and also book accommodation.)

A: 환전도 해야 해요. 한국은 현금을 많이 써요. (You also have to exchange money. Korea uses a lot of cash.)

B: 맞아요. 할 게 정말 많네요. (Right. There's really a lot to do.)

📍 Conversation 3: Health advice

A: 요즘 너무 피곤해요. (I've been so tired lately.)

B: 얼마나 자요? (How much do you sleep?)

A: 하루에 네다섯 시간밖에 못 자요. (I can only sleep about 4–5 hours a day.)

B: 그러면 안 돼요! 최소 7시간은 자야 해요. (That won't do! You have to sleep at least 7 hours.)

A: 알아요. 일이 너무 많아서요. (I know. I just have too much work.)

~아/어야 해요 vs ~아/어야 돼요

You'll often hear both 해요 and 돼요 used with ~아/어야:

In everyday conversation, both are completely interchangeable. Don't overthink the difference — use whichever feels natural.

가야 해요. = 가야 돼요. (I have to go.)

Common Mistakes to Avoid

❌ Mistake 1: "Don't have to" ≠ 안 ~아/어야 해요

❌ 안 가야 해요. (means "I must not go" - prohibition) ✅ 가지 않아도 돼요. (I don't have to go - no obligation)

❌ Mistake 2: Wrong vowel choice

❌ 먹아야 해요 ✅ 먹어야 해요 (먹 has ㅓ → 어야)

❌ 공부하어야 해요 ✅ 공부해야 해요 (하다 → 해야)

❌ Mistake 3: Overusing for soft suggestions

~아/어야 해요 carries a sense of obligation or necessity. For soft suggestions, use ~는 게 좋을 것 같아요 or ~아/어 보세요 instead.

Quick Practice

Translate using ~아/어야 해요:

1. I have to go to the bank today.
2. You have to try Korean food.
3. I had to wake up at 5 AM.
4. We'll have to decide soon.
5. You have to rest when you're sick.

Answers:

1. 오늘 은행에 가야 해요.
2. 한국 음식을 먹어야 해요.
3. 새벽 다섯 시에 일어나야 했어요.
4. 곧 결정해야 할 거예요.
5. 아플 때는 쉬어야 해요.

Summary

~아/어야 해요 is one of those patterns that immediately makes your Korean feel more real - because real life is full of things you have to do. Once this is natural, you can talk about deadlines, advice, plans, and responsibilities with ease.