은/는 vs 이/가: A Formal Guide to Korean Topic and Subject Markers
This article explains the Korean particles 은/는 and 이/가 in a formal and practical manner. It defines core meanings, offers minimal pairs, and presents distributional rules that support accurate writing. Examples are original and designed for English-speaking learners. The tone is consistent and objective.
Definition and scope
이/가 marks a grammatical subject and often introduces new or focal information. 은/는 marks a topic or contrast frame and often refers to known, accessible, or deliberately contrasted information. Both particles attach to nouns and do not inflect for tense or politeness. Writers choose between them according to discourse status and emphasis.
Minimal pairs: new vs. known information
Introducing new information with 이/가
When the sentence presents newsworthy or newly highlighted content, 이/가 is preferred.
- 새 공지가 올라왔습니다. — A new announcement has been posted.
- 문제 원인이 확인되었습니다. — The cause has been identified.
Framing known or contrasted content with 은/는
When the sentence sets a frame, shifts topic, or contrasts alternatives, 은/는 is used.
- 오늘은 일정이 변동되었습니다. — As for today, the schedule changed.
- 해당 항목은 필수입니다. — This item, for its part, is mandatory.
Focus and contrast in assertions
Contrastive reading of 은/는
은/는 can imply an unspoken alternative and restrict the claim to the topic. This reading is frequent in comparisons and policy notes.
- 배송료는 무료입니다. — The shipping fee is free (other fees may not be).
Exhaustive tendency of 이/가
In certain contexts, 이/가 reads as “it is X (and not Y).” It suits answers to selection questions and responsibility statements.
- 담당자가 승인했습니다. — It is the manager who approved it.
Predicate type and common environments
Existence, appearance, and events
Event reports, first mentions, and existence statements usually take 이/가.
- 오류가 발생했습니다. — An error occurred.
- 자리가 없습니다. — There is no seat.
General statements and evaluations
Summaries, general truths, and evaluations about a set commonly take 은/는.
- 이 서비스는 안정적입니다. — As for this service, it is stable.
- 한국 겨울은 건조합니다. — Korean winters, in general, are dry.
Questions, answers, and information flow
Answering “what happened?” with 이/가
When the predicate carries the informational peak, 이/가 aligns with the focus.
- 누가 보고했습니까? — 김 팀장이 보고했습니다. — Who reported it? Manager Kim did.
Maintaining a topic with 은/는
When the topic remains constant across sentences, 은/는 preserves coherence.
- 해당 부서는 계획을 제출했습니다. 일정은 다음 주에 확정됩니다.
Negation, emphasis, and polarity
Negation with identification
Negative identification places focus on the subject; 이/가 is natural. Contrastive framing uses 은/는.
- 원인이 아닙니다. — It is not the cause.
- 시간은 문제가 아닙니다. — As for time, it is not the issue.
Emphatic confirmation
Affirmations that answer doubts can use 이/가 for tight focus.
- 해결책이 맞습니다. — This solution is correct.
Topic resets and contrastive paragraphs
Paragraph-initial topics with 은/는
At the start of a paragraph, 은/는 flags the next set of statements as belonging to the topic. This improves readability in guides and reports.
- 보안 정책은 다음 원칙을 따릅니다. — The security policy follows these principles.
Switching topics responsibly
When a paragraph changes scope, a new 은/는 topic prevents ambiguity between references.
- 모바일 앱은 업데이트가 완료되었습니다. 웹 버전은 내일 적용됩니다.
Common learner errors and precise fixes
Using 은/는 for first mentions
Error: 새 공지는 올라왔습니다. (first mention) Fix: 새 공지가 올라왔습니다.
Dropping contrast that the context requires
Error: 주말이 가능합니다. (schedule comparison context) Fix: 주말은 가능합니다.
Overusing 이/가 in general statements
Error: 이 매뉴얼이 의무입니다. (policy tone) Fix: 이 매뉴얼은 의무입니다.
Interaction with other particles
Stacking with topic and subject
Only one of 은/는 or 이/가 appears on the same noun phrase. When emphasis requires both notions, writers restructure the sentence rather than stack markers.
Topic with case-marked phrases
Topicalization of other case-marked phrases is possible but should be controlled in formal prose to avoid heavy openings.
- 비용은 회사가 부담합니다. — As for the cost, the company bears it.
Applied practice (original)
Task 1: Choose the marker
- ( ) 문제가 보고되었습니다. → 문제가 보고되었습니다: 이/가.
- ( ) 접속은 안정적입니다. → 접속은 안정적입니다: 은/는.
- ( ) 담당자가 승인했습니다. → 담당자가 승인했습니다: 이/가.
Task 2: Rewrite for contrast
- 저녁이 가능합니다 → 저녁은 가능합니다.
- 이 모델이 빠릅니다 → 이 모델은 빠릅니다. (comparison context)
Task 3: Repair first mention
- 새 일정은 등록되었습니다 → 새 일정이 등록되었습니다.
Summary and conclusion
이/가 presents subjects as new or focal information and fits existence, events, and precise identification. 은/는 frames topics, expresses contrast, and supports summaries and general statements. Correct selection depends on information flow, paragraph structure, and the communicative goal of each sentence. Consistent application improves readability and prevents unintended emphasis in formal Korean prose.
