하다 or 되다: how do you know which one a Korean verb needs?

Open almost any Korean news article and you will meet the same root twice in different clothes: 회의를 시작했다 in one line, 회의가 시작됐다 two lines later. Both come out as some version of “the meeting began.” Swap the endings and the sentence still parses, which is exactly the trap — 하다 and 되다 are not two spellings of one idea. They are different words with different dictionary entries, and one of them is quietly telling you whether anyone did anything.

How do I know if a Korean verb needs 하다 or 되다?

Check whether the sentence names someone doing the action to a target. If it does, or could, that target takes 을/를 and the verb is 하다 — an ordinary transitive verb, needing a direct object the same way 보다 (“to watch”) does. If nobody is named — the sentence is just reporting that something happened to the target — that target takes 이/가 instead and the verb is 되다, intransitive, no object at all (한국민족문화대백과사전, “동사”).

회의를 시작하다 — someone starts the meeting. 회의가 시작되다 — the meeting starts, no one named.

예약을 취소하다 — someone cancels the reservation. 예약이 취소되다 — the reservation gets canceled, no one named.

The pattern: 하다 acts on it, 되다 happens to it

A lot of everyday Sino-Korean nouns (한자어) name an event that has two sides: an agent’s side and a target’s side. Add 하다 and you’re narrating from the agent’s side. Add 되다 and you’re narrating from the target’s side. Same event, two grammatical cameras — and 표준국어대사전 defines each 되다 form on its own terms, from the target’s point of view, not as “passive of X하다”:

한자어	X를 ~하다 (agent’s side)	X가 ~되다 (target’s side)	표준국어대사전 definition
시작 (始作)	회의를 시작하다 — starts the meeting	회의가 시작되다 — the meeting begins	“어떤 일이나 행동의 처음 단계가 이루어지다”
해결 (解決)	문제를 해결하다 — solves the problem	문제가 해결되다 — the problem gets solved	“제기된 문제가 해명되거나 얽힌 일이 잘 처리되다”
확인 (確認)	예약을 확인하다 — confirms the reservation	예약이 확인되다 — the reservation is confirmed	“틀림없이 그러한가가 알아보아지거나 인정되다”
취소 (取消)	예약을 취소하다 — cancels the reservation	예약이 취소되다 — the reservation gets canceled	“발표된 의사가 거두어들여지거나 예정된 일이 없어지다”
사용 (使用)	이 자료를 사용하다 — uses this material	이 자료가 사용되다 — this material gets used	“일정한 목적이나 기능에 맞게 쓰이다”
완성 (完成)	작품을 완성하다 — completes the work	작품이 완성되다 — the work gets completed	“완전히 다 이루어지다”

Notice the definitions never mention an agent. 해결되다 is “a problem gets clarified or handled” — the dictionary does not say by whom, because 되다’s whole job is to leave that slot empty.

Not every 하다 verb has a 되다 partner

This only works when the noun names an event that can happen to a target with nobody doing it. Some Sino-Korean 하다 verbs name a pure activity that exists only because an agent performs it — there is no free-floating “studying event” out in the world waiting to happen to something. 표준국어대사전 has no entry at all for 공부되다 or 노력되다: zero results for either, checked directly against the dictionary rather than assumed. 공부하다 (“to study”) and 노력하다 (“to make an effort”) stay 하다-only.

So the working test isn’t “can I mechanically swap the ending” — it’s “does this noun describe something that happens to a patient, or something only an agent does.” When you’re not sure, check the dictionary before producing a 되다 form you’ve never actually met. Guessing one into existence is the same mistake as inventing a polite ending a verb doesn’t have: sometimes the slot is just empty, and the fix is to rephrase, not to force the pattern.

One flag: this is the same 되다 you already know as “become” — 의사가 되다 (“become a doctor”), 다 됐어 (“it’s ready”). With an ordinary noun like 의사, 되다 means the subject turns into that thing — it isn’t marking an agent-less version of a 의사하다 you’d never say. The X가 ~되다 pattern in this article only kicks in for event nouns that already have, or could have, a 하다 reading.

되다 in the news, 하다 in the room

The register split follows straight from the grammar. News and official writing lean on 되다 because reporting an outcome without naming who’s responsible is exactly what a headline or an announcement needs: 공사가 완료됐다 (“construction is complete”) doesn’t have to say who finished it. In conversation about your own life, you’re usually the one doing things, so 하다 forms dominate: 이거 내가 다 확인했어 (“I checked all of this myself”). When a 되다 form does show up in casual speech, it’s almost always about something that happened to you rather than something you’re reporting on: 예약이 취소됐어 is a complaint, not a press release.

What to take from this

• 하다 needs an object: X를 ~하다, an agent acting on X.
• 되다 drops the object: X가 ~되다, X undergoing the event with nobody named.
• Many 한자어 support both because the underlying event has an agent’s side and a target’s side — 시작, 해결, 확인, 취소, 사용, 완성 among them.
• Some 한자어 only support 하다 because they name a pure activity, not something that happens to a target — 공부 and 노력 are two, and 표준국어대사전 has no 되다 entry for either.
• When you’re not sure a 되다 form exists, check before you use it — don’t extend the pattern by ear.

None of this sticks from a table, though — it sticks from noticing the choice while you’re reading, the same way you’d notice a friend switch from 반말 (casual, no-honorifics speech) to 존댓말 (polite speech) mid-conversation. That’s the same argument as how I improved my Korean listening: the pattern lands when you meet it inside sentences drawn from what you’re actually studying, not a list built for everyone. up103 builds that kind of reading and listening practice out of the notes you already keep, and Founding Learners get 6 months free, then 50% off for life, at app.up103.com.

— 에드, up103