One Rule, With Particles as the Exception
The Korean Orthography Rules (Hangeul Matchumbeop), General Provisions, Clause 2, require each word in a sentence to be separated by a space. Particles, covered in Article 41, are an exception. Although particles are words, they cannot stand alone, so they are joined to the preceding word. Even when two or more particles appear in succession, as in '꽃이', '꽃마저', and '꽃에서부터', they are joined. The same applies when a particle follows an ending, as in '사과하기는커녕'[1].
Much of the uncertainty about spacing therefore comes down to the question, "Is this a particle or a bound noun?"
Join After a Substantive, Separate After a Modifier
Article 42 requires bound nouns to be separated by spaces. Its explanation pairs bound nouns with particles that have the same form. You can tell which is which by looking at the preceding word. After a substantive such as a noun or pronoun, the word is a particle and is joined to it. After the adnominal form of a predicate, such as '웃을' or '아는', it is a bound noun and is separated by a space[1].
The criterion for '만' is slightly different. When it expresses limitation or comparison, as in '하나만 알고 둘은 모른다', it is a particle and is joined to the preceding word. When it indicates elapsed time or a number of occurrences, as in '떠난 지 사흘 만에 돌아왔다' and '세 번 만에 시험에 합격했다', it is a bound noun and is separated by a space[1].
'-ㄴ지' and '지', '-듯' and '듯'
'지' has the same form whether it is part of an ending or a bound noun. In '집이 큰지 작은지 모르겠다' and '어떻게 할지 모르겠다', '지' is part of the endings '-(으)ㄴ지, -ㄹ지', so it is joined to the preceding word. When it indicates elapsed time, as in '그가 떠난 지 보름이 지났다', it is a bound noun and is separated by a space[1].
'듯' works similarly. After the stem of a predicate, it is an ending and is joined to it, as in '구름에 달이 흘러가듯'. After an adnominal form, it is a bound noun and is separated by a space, as in '그가 먹은 듯'[1].
Numbers and Units Are Spaced by Default but May Be Joined
Article 43 requires nouns denoting units to be separated by spaces. '차 한 대', '옷 한 벌', and '집 한 채' follow the default rule. However, these nouns may be joined when indicating order or used with Arabic numerals. One example in the rules is '1446년 10월 9일'. The explanation presents '2 시간' as the default and '2시간' as an allowed form. It also explains that the joined form is more common in practice because it is easier to read[1].
When writing numbers in Hangul, Article 44 calls for spaces between units of ten thousand. Write '십이억 삼천사백오십육만 칠천팔백구십팔', or '12억 3456만 7898' when combining Hangul with numerals. Monetary amounts are an exception. The explanation notes that, to prevent tampering, it is customary to write them without spaces, as in '일금: 삼십일만오천육백칠십팔원정'[1].
When Auxiliary Predicates Can and Cannot Be Joined
Article 47 requires auxiliary predicates to be separated by spaces as a default, but allows them to be joined in some cases. Both '불이 꺼져 간다' and '불이 꺼져간다' are correct, as are '그 일은 할 만하다' and '그 일은 할만하다'[1].
The rules also specify cases where joining is not allowed[1].
Conversely, in some cases joining is the default. '-아/-어 지다' and '-아/-어 하다' are joined, as in '낙서가 지워진다' and '아기를 예뻐한다'. However, when '-아/-어 하다' attaches to an entire phrase, it is separated by a space, as in '먹고 싶어 하다' and '마음에 들어 하다'[1].
| Case | Joining | Example |
|---|---|---|
| Where joining is allowed | Spaced by default; joining allowed | 불이 꺼져 간다, 불이 꺼져간다 / 그 일은 할 만하다, 그 일은 할만하다 |
| Particle attached to preceding word | Cannot be joined | 직접 먹어도 보았다(○) / 직접 먹어도보았다(×) |
| Preceding word is a compound predicate | Cannot be joined | 쫓아내 버렸다(○) / 쫓아내버렸다(×) |
| Sentence-final ending before auxiliary predicate | Cannot be joined | 책상이 작은가 싶다, 그가 밥을 먹나 보다 |
| '-아/-어 지다', '-아/-어 하다' | Joined by default | 낙서가 지워진다, 아기를 예뻐한다 |
| '-아/-어 하다' attached to an entire phrase | Separate with a space | 먹고 싶어 하다, 마음에 들어 하다 |
Where to Check When in Doubt
If the rules alone don't settle how to write a word, check whether it is listed as a single word in the Standard Korean Language Dictionary. The explanation of the rules also states that '도와드리다' is always joined, in keeping with the dictionary entry for '도와주다'[1]. If you can't find it in the dictionary either, you can ask the National Institute of Korean Language's Online Ganada Q&A service[2].
References
- [1] National Institute of Korean Language, Korean Orthography Rules (Hangeul Matchumbeop), Chapter 5, Spacing (Korean Language Norms).
- [2] National Institute of Korean Language, Online Ganada Q&A service.
Frequently asked questions
Is it wrong to write '2시간' without a space?
No. Article 43 requires nouns denoting units to be separated by spaces as a default, but also allows them to be joined when used with Arabic numerals. The explanation likewise presents '2 시간' as the default and '2시간' as an allowed form.
Which is correct, '할 만하다' or '할만하다'?
Both are correct. Article 47 requires auxiliary predicates to be separated by spaces as a default, but also allows them to be joined. However, they cannot be joined if a particle is attached to the preceding word or if that word is a compound predicate. That is why '직접 먹어도보았다' and '쫓아내버렸다' are incorrect.