Three Ways to Say No
Korean has short negation with 안, short negation with 못, and long negation with 지 않다. The first two are about meaning, the third is about register and length.
That single contrast — choosing not to versus being unable to — is the one examiners and native speakers notice immediately.
안: Refusal and Non-Doing
안 goes directly before the verb. It states that the action does not happen, whether by choice or by fact.
하다 verbs split
With 하다 verbs, 안 goes before 하다, splitting the noun away: 공부하다 becomes 공부 안 해요, not 안 공부해요.
못: Inability and Circumstance
못 means cannot — because of skill, time, permission or an external obstacle. It carries no suggestion of refusal.
안 versus 못 in one line
안 is I will not. 못 is I cannot. If someone offers you cake and you are full, 안 먹어요. If you are allergic, 못 먹어요.
지 않다 and 지 못하다
The long forms attach to the stem and are used in writing, formal speech and where the short form would sound blunt.
In TOPIK writing, 지 않다 is the safer choice because it reads as controlled and formal. In conversation, 안 is more natural and shorter.
Negating Nouns and Existence
있어요 and 알아요 do not take 안. Use 없어요 and 몰라요 instead — 안 있어요 is a classic beginner error.
Common Mistakes
Practice
Choose 안 or 못, then give the long form.
- I am not eating because I am full.
- I cannot eat shellfish.
- I cannot speak Chinese.
- I did not study yesterday.
- I do not have time.
For the endings these attach to, see Korean verb conjugation, and for linking the clauses, Korean connectors.
FAQ
What is the difference between 안 and 못?
안 means you do not do something, usually by choice or as a simple fact. 못 means you cannot, because of ability, permission or circumstance. 안 먹어요 is "I am not eating"; 못 먹어요 is "I cannot eat it".
Is 지 않다 more formal than 안?
It is longer and reads as more controlled, so it suits writing, news and formal speech. In conversation 안 is more common and more natural. Neither is rude; they differ in register rather than politeness level.
Why can I not say 안 있어요?
Because 있다 and 없다 form a pair, and 없다 is already the negative of 있다. The same applies to 알다 and 모르다. Saying 안 있어요 marks a beginner immediately.
Where does 안 go in a 하다 verb?
Between the noun and 하다: 공부 안 해요, 운동 안 했어요. Putting it before the whole verb, as in 안 공부해요, is understood but unnatural in modern Korean.