안 vs 못

Explanation

안 negates volition or simple non-occurrence: you don’t do it (by choice or general no). 오늘 안 가요 — I’m not going today.

못 marks inability or failure: you can’t / couldn’t. 한국어를 잘 못해요 — I’m not good at Korean / I can’t speak it well.

Word order: 안/못 usually sits right before the verb (or adjective). 안 먹어요 / 못 먹어요.

Past: 안 갔어요 (didn’t go) vs 못 갔어요 (couldn’t go). The second often implies obstacle, illness, traffic, prohibition, or lack of skill.

With 잘, 못 is extremely common for skills: 노래를 잘 못해요. Using 안 here can sound like refusal rather than ability.

Some fixed patterns prefer one or the other; when unsure, ask: is this choice or ability? That single question picks the right particle-like adverb.