KGYSAK: 되 vs. 돼

For lack of a more accurate grammatical explanation, 되다 is conjugated as 돼 in usual speech. Examples include 해도 돼요?" (Can I do it?) and "만지면 안 돼요" (Don't touch [that]) . The opposite is when the verb is used in connection with other forms such as "교수이 되고 싶어요" (I want to be a professor) and "...안되면..." (...if you don't do it...) My confusion comes when to use which spelling? For all intents and purposes, the pronunciation is the same.

정민, fellow Korean history nerd, friend and diligent corrector of all mistakes Korean, taught me this really helpful mental trick to think of when confused with which spelling to use. Here's the trick:


If you can replace '되' with '하' then you have the right spelling
ex) 안 하다 -> 안 되다
ex) 안 하면 -> 안 되면
ex) 하지만 -> 되지만
ex) 하잖아 -> 되잖아
ex) 항거야 -> 될거야

If you can replace '돼' with '해' then you have the right spelling

ex) 안 해 -> 안 돼

ex) 안 해서 -> 안 돼서

ex) 했어 -> 됐어

ex) 해야 해요 -> 해야 돼요

try flipping the rule to see if it works for you.