-었-/-았- | what is -었-/-았-? | Korean past tense marker | usage & examples
-었-/-았- is the core past marker in Korean. It attaches to verb and adjective stems and combines with sentence endings to express completed events, past states, and present results of past actions. This article explains the formation rule, common patterns in polite style, semantic nuances, and frequent learner errors.
Definition and scope
-었-/-았- is an infix placed between the stem and the final ending. It typically signals that the event or state is located before the speech time. In many contexts it also implies completion or a resulting state. The choice between -었- and -았- follows a regular vowel harmony rule based on the stem vowel, with a few predictable irregular patterns.
Form and vowel harmony rule
Basic selection: -았- after ㅏ/ㅗ, -었- after other vowels
For regular verbs and adjectives, the past marker is selected as follows.
- Stem with ㅏ or ㅗ → -았-
- 가다 → 가았습니다 → 갔습니다.
- 오다 → 오았습니다 → 왔습니다.
- Stem with other vowels (ㅓ, ㅜ, ㅡ, ㅣ, ㅐ, ㅔ 등) → -었-
- 먹다 → 먹었습니다.
- 보내다 → 보내었습니다 → 보냈습니다.
- 걸다(전화하다 의미) → 걸었습니다.
Actual surface forms frequently contract for ease of pronunciation, but the underlying selection rule 유지했습니다.
하다 verbs and the special form 했-
Verbs with the stem 하- combine with -였-, which contracts to -했-.
- 공부하다 → 공부했습니다.
- 설명하다 → 설명했습니다.
- 준비하다 → 준비했습니다.
Common contractions learners will meet
In writing and speech, several combinations contract in a regular way.
- 가 + 았 + 어요 → 갔어요.
- 보내 + 었 + 어요 → 보냈어요.
- 기다리 + 었 + 어요 → 기다렸어요.
Formal -습니다 style keeps the same contracted stems: 갔습니다, 보냈습니다, 기다렸습니다처럼 표기했습니다.
Past events and completed actions
Single past event
-었-/-았- marks an event that finished in the past. The time expression may appear explicitly or be understood from context.
- 어제 보고서를 제출했습니다. — The report was submitted yesterday.
- 지난주에 새로운 버전을 배포했습니다. — A new version was released last week.
Repeated events in a past period
With temporal adverbs like 자주, 여러 번, 동안, the same form describes repeated events inside a finished interval.
- 시험 기간 동안 늦게까지 공부했습니다. — During the exam period, (we) studied until late.
- 여러 번 확인했지만 오류를 찾지 못했습니다. — It was checked many times but the error was not found.
Resultative and experiential readings
Present result of a past even
In many contexts, -었-/-았- implies that a past action has a current result.
- 설치를 모두 완료했습니다. — The installation has been completed and is now in a completed state.
- 계정을 생성했습니다. — An account has been created and still exists.
Experience up to now
With phrases like 한 번도, 여러 번, 지금까지, the same marker expresses life experience up to the present.
- 지금까지 온라인 강의를 여러 번 수강했습니다. — Up to now, online courses have been taken many times.
- 이 기능을 한 번도 사용하지 않았습니다. — This feature has never been used.
Past states with adjectives
Temporary states and conditions
Adjectival stems with -었-/-았- describe states that held in the past.
- 당시 연결이 매우 불안정했습니다. — At that time, the connection was very unstable.
- 첫 버전은 인터페이스가 복잡했습니다. — The first version had a complex interface.
Change of state with 되다 and 나다
Verbs like 되다 and 나다 describe the moment a state started or an event occurred.
- 문제가 해결되었습니다. — The problem became resolved.
- 오류가 발생했습니다. — An error occurred.
Combination with polite endings
-었습니다 / -았습니다 in formal style
For very formal reports, announcements, and manuals, -었-/-았- combines with -습니다.
- 점검을 완료했습니다. — The inspection has been completed.
- 변경 사항을 안내해 드렸습니다. — The changes have been communicated.
-었어요 / -았어요 in polite conversational style
In spoken interaction and neutral writing, -어요 style is common.
- 어제 새 계정을 만들었어요. — I created a new account yesterday.
- 이미 읽어 봤어요. — I have already read it.
Negation, questions, and complex predicates
Negation with -지 않았다 and 못 했다
Past negation uses the same marker on 않다 or on main verbs with 못.
- 예정된 시간에 시작하지 않았습니다. — It did not start at the scheduled time.
- 시간이 부족해서 테스트를 충분히 하지 못했습니다. — There was not enough time, so testing could not be done sufficiently.
Questions with past markers
Interrogatives keep the same past infix and change only the final ending.
- 문서를 모두 확인했습니까? — Did you check all the documents?
- 어디에서 접속했습니까? — From where did you access it?
Combined with auxiliary constructions
With constructions such as -아/어 보다, -아/어 놓다, -아/어 두다, the past marker usually appears on the last verb.
- 여러 방법을 시도해 보았습니다. — Several methods have been tried.
- 파일을 미리 저장해 두었습니다. — The file was saved in advance and remains saved.
Common learner errors and corrections
Omitting the past marker
Error: 어제 보고서 제출합니다. Fix: 어제 보고서를 제출했습니다.
Using wrong vowel harmony
Error: *먹았습니다 → 먹았습니다(표기 자체는 맞지만 발음을 혼동하는 경우가 많습니다).* Correct understanding: 먹다 + 었다 → 먹었다 → 먹었습니다.
Using present tense for finished procedures
Error: 설치를 모두 완료합니다. (이미 끝난 상황 보고) Fix: 설치를 모두 완료했습니다.
Overusing progressive markers with past
Error: 어제는 계속 일하고 있었습니다 to report a simple finished day. Fix: 어제는 계속 일했습니다. — A simple narrative past is often sufficient.
Original practice tasks
Task 1: Convert present to past
- 지금 안내 메일을 보냅니다. → 방금 안내 메일을 보냈습니다.
- 오늘 결과를 공유합니다. → 오늘 결과를 공유했습니다.
- 지금 오류를 수정합니다. → 방금 오류를 수정했습니다.
Task 2: Describe a past state with adjectives
- 서버가 안정적입니다. (어제 상황) → 어제 서버가 안정적이었습니다.
- 인터페이스가 단순합니다. (첫 버전 설명) → 첫 버전은 인터페이스가 단순했습니다.
Task 3: Write past experience sentences
- I have used this function several times. → 이 기능을 여러 번 사용했습니다.
- I have never seen that error message. → 그 오류 메시지를 한 번도 본 적이 없습니다.
Conclusion
-었-/-았- is the central device for expressing past time and completed events in Korean. It follows a stable vowel harmony rule, combines smoothly with formal endings such as -습니다/-했습니다, and supports both simple past narratives and present-result readings.
