2 · Helping verbs and modal patterns
May and must not: -아도/어도 되다, -(으)면 안 되다
permission and prohibition
"Even if you do it, it is fine" gives permission; "if you do it, it is not fine" forbids it.
Permission uses -아도/어도, "even if", with the same vowel choice as -아요/어요, followed by 되다, "to work out, to be all right": 가도 돼요, 먹어도 돼요, 해도 돼요. Literally "even if you go, it is fine". As a question it asks for permission: 여기 앉아도 돼요?, "may I sit here?" — and the answer repeats it, 네, 앉아도 돼요, or simply invites: 네, 앉으세요.
Prohibition turns it round with -으면, "if": 가면 안 돼요, 먹으면 안 돼요, "if you eat it, it is not all right". After a vowel or a stem ending in l the ending is -면 (만들면), after other consonants -으면. This is the everyday "must not", used for rules, warnings and parents' instructions alike.
Between them they fill a grid that English handles with four confusable modal verbs: 가야 해요 "must go", 가도 돼요 "may go", 안 가도 돼요 "don't have to go" and 가면 안 돼요 "must not go". The third one is permission to do nothing — 안 before the verb, or -지 않아도 되다 in more careful speech.
괜찮다 can stand in for 되다 and sounds softer: 먹어도 괜찮아요?, "is it all right if I eat this?". With someone senior, 될까요? is softer still: 하나 여쭤봐도 될까요?, "may I ask you something?". Watch the spelling: 되다 plus -어요 is always 돼요, never 되요.
The form
| may (last vowel a or o) | 가다 → 가도 돼요 |
| may (other vowels) | 먹다 → 먹어도 돼요 |
| asking permission | 여기 앉아도 돼요? |
| must not | 먹으면 안 돼요 |
| don't have to | 안 와도 돼요 |
| softer | 먹어도 괜찮아요? |
The rules one by one
The form this topic is aboutThe word that calls for it
-아도/어도 되다 gives or asks for permission.
창문을 열어도 돼요?May I open the window?
-으면 안 되다 forbids; after a vowel or a stem in l the ending is -면.
여기에서 사진을 찍으면 안 돼요.You must not take photos here.
"Don't have to" is 안 plus -아도/어도 되다, not a negated "must".
내일은 일찍 안 와도 돼요.You don't have to come early tomorrow.
괜찮다 can replace 되다 and sounds softer.
이거 하나 먹어도 괜찮아요?Is it all right if I have one of these?
A closer look
Four answers to one question
Asked 내일 가야 돼요?, "do I have to go tomorrow?", a Korean speaker can answer in four ways, and each maps onto one English modal: 네, 가야 돼요 "yes, you must", 아니요, 안 가도 돼요 "no, you needn't", 가도 되고 안 가도 돼요 "you may or may not — it's up to you", and 아니요, 가면 안 돼요 "no, you mustn't".
English speakers mix up "must not" and "don't have to" because both contain a "not" in front of an obligation. Korean keeps them apart by building them from different pieces — "if" for the prohibition, "even if" for the permission — so it helps to think in those pieces rather than in translations.
How to spot it
- -아도/어도 되다
- -(으)면 안 되다
- 괜찮아요
- 돼요?
Example sentences
화장실 좀 써도 돼요?May I use the toilet?
그 의자에 앉으셔도 돼요.You are welcome to sit on that chair.
수업 시간에 휴대폰을 사용하면 안 돼요.You must not use your phone during class.
이 강은 깊어서 수영하면 안 돼요.This river is deep, so you must not swim in it.
오늘은 숙제를 안 해도 돼요.You don't have to do any homework today.
늦게 와도 되지만 미리 연락해 주세요.You can come late, but please let me know beforehand.
8 more example sentences
이 옷 한번 입어 봐도 돼요?May I try this on?
필요하면 제 우산을 쓰셔도 돼요.If you need it, you are welcome to use my umbrella.
도서관에서 큰 소리로 이야기하면 안 돼요.You must not talk loudly in the library.
아직 열이 있으니까 밖에 나가면 안 돼요.You still have a temperature, so you mustn't go out.
돈은 나중에 줘도 돼요.You can give me the money later.
이 서류는 안 내도 돼요.You don't need to hand in this form.
지금 전화해도 괜찮아요?Is it all right if I call now?
술을 마시고 운전하면 절대 안 돼요.You must never drink and drive.
Worth knowing (1)
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돼요, never 되요
Where -어 follows the stem, 되 and 어 merge: 돼요, 됐어요, 돼서. Where it does not — 되고, 되지만, 되는 — the stem stays 되. A quick test: where 하다 would give 해, write 돼; where it would give 하, write 되.
여기 주차해도 돼요?May I park here?
The trap English speakers fall into
Watch out
되다 plus -어요 contracts to 돼요. Many Koreans misspell it too, but on paper it is always 돼요, 됐어요, 돼서.
Even if you do it, it works: permission. If you do it, it does not work: forbidden.
Your turn
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