Why is 돼요 correct, but 되요 is not?

The shortcut is simple: 돼 is the contraction of 되어. Since 되어 + 요 becomes 되어요, its contracted form is 돼요.

If the form can expand naturally to 되어, use 돼: 됐다 → 되었다, 돼서 → 되어서.

Keep 되- in forms such as 되고, 되면 and 되지, where -어 is not attached.

Sources & context

2026-09-18