2 · Helping verbs and modal patterns
Must and have to: -아야/어야 하다
obligation
The verb takes -아야/어야, "only if", and 하다 or 되다 follows: it has to be done.
The ending -아야/어야 chooses its vowel exactly like the polite -아요/어요: 가야, 먹어야, 마셔야, and 해야 for every 하다 verb. Irregular stems behave as they do before -아요: 들어야, 도와야, 써야. After it comes 하다 or 되다: 가야 해요 or 가야 돼요. In speech 돼요 is very common; in writing 해야 한다 and 해야 합니다 are the usual forms.
On its own -아야/어야 means "only if": 연습해야 늘어요, "you only improve if you practise". So 가야 해요 is, at heart, "only if I go does it work" — and that covers "must", "have to" and "need to". The past goes on the second verb: 가야 했어요, "I had to go".
The negative is where English speakers go wrong. "I don't have to go" is not 안 가야 해요; that would say that not going is required. Korean says "even if I don't go, it is fine": 안 가도 돼요. "Must not" is different again: 가면 안 돼요. Those two patterns are the next topic.
The pattern also gives strong advice, especially with 꼭: 이 영화는 꼭 봐야 해요, "you really must see this film". Telling someone senior what they have to do sounds less abrupt with the honorific: 여기에 성함을 쓰셔야 돼요, "you will need to write your name here".
The form
| last vowel a or o | 가다 → 가야 해요 |
| other vowels | 먹다 → 먹어야 해요 |
| 하다 verbs | 하다 → 해야 해요 |
| with 되다 | 가야 돼요 |
| had to | 가야 했어요 |
| honorific | 가셔야 해요 |
The rules one by one
The form this topic is aboutThe word that calls for it
-아야/어야 takes the same vowel as the polite ending -아요/어요.
내일 아침 일찍 일어나야 해요.I have to get up early tomorrow morning.
Both 하다 and 되다 follow it; 돼요 is the more common in speech.
이 약은 식사 후에 드셔야 돼요.You need to take this medicine after meals.
The past goes on 하다 or 되다.
어제는 늦게까지 일해야 했어요.Yesterday I had to work until late.
꼭 makes the obligation stronger, or turns it into a strong recommendation.
부산에 가면 꼭 시장에 가 봐야 해요.If you go to Busan, you really must visit the market.
A closer look
"Only if" on its own
The ending lives a life of its own outside this pattern, and seeing it there makes the obligation easier to feel. 먹어야 살아요 is "you have to eat to live", literally "only if you eat do you live"; 직접 봐야 알아요, "you will only know once you see it for yourself".
With -지 after it, the same ending becomes a resolution spoken half to oneself: 내일부터 운동해야지, "right, from tomorrow I'm exercising". Said to someone else with -지요, it is a friendly "of course you should": 당연히 쉬어야지요.
How to spot it
- -아야/어야 하다
- -아야/어야 되다
- 꼭
- 반드시
Example sentences
오늘 저녁까지 보고서를 끝내야 해요.I have to finish the report by this evening.
비자를 받으려면 여권 사진이 있어야 돼요.To get a visa you need a passport photo.
수업에 늦지 않으려면 지금 출발해야 해요.If I don't want to be late for class, I have to leave now.
시험 때문에 주말에도 공부해야 했어요.Because of the exam I had to study at the weekend too.
이 서류는 반드시 본인이 직접 제출해야 합니다.This form must be handed in by the applicant in person.
건강을 지키려면 물을 많이 마셔야 돼요.To stay healthy you should drink plenty of water.
8 more example sentences
지하철에서 내려서 버스로 갈아타야 해요.You have to get off the underground and change to a bus.
손님이 오시니까 집을 청소해야 돼요.Guests are coming, so I have to clean the house.
한국에서는 집에 들어갈 때 신발을 벗어야 해요.In Korea you have to take your shoes off when you go into a home.
저는 내일 병원에 가야 돼서 회사에 못 가요.I have to go to hospital tomorrow, so I can't go to work.
표가 없어서 한 시간 동안 기다려야 했어요.There were no tickets, so we had to wait for an hour.
발표 자료를 다시 만들어야 할 것 같아요.I think I will have to redo the presentation slides.
아이는 밤 아홉 시에는 자야 해요.The child has to go to bed at nine.
이 서류 어디에 사인해야 돼요?Where do I have to sign this form?
Worth knowing (1)
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-아야지: talking to yourself
With -지, the ending turns into a resolution, the sentence a person says to themselves before getting up from the sofa. It belongs to informal speech.
이제 진짜 공부해야지.Right, now I really have to study.
The trap English speakers fall into
Watch out
"Don't have to" is not a negated "must". 안 가야 해요 says that not going is required. Korean says that not going is fine: 안 가도 돼요.
Verb plus -aya or -eoya, then haeyo or dwaeyo: only if it is done does it work.
Your turn
9 exercises on this topic. Your answers are checked in the browser; none of them leaves your device.