In short

해요체 is the polite everyday speech level, and it is made by one small move: take the 아/어 form you already built in lesson 10 and add 요. The same form does four jobs - statement, question, request and suggestion - and only intonation and context tell them apart.

The rule

Step 1 - The whole recipe is “아/어 form + 요”

Verb or adjective stem + -아/어 + 요

Lesson 10 gave you the engine: a stem whose last vowel is ㅏ or ㅗ takes -아, everything else takes -어, and 하- takes 여 -> 해. 해요체 adds nothing new. It just glues 요 onto that form.

먹다 -> stem 먹- -> 먹어 -> 먹어요 (meogeoyo, eat); 가다 -> 가- -> 가 -> 가요 (gayo, go); 하다 -> 해 -> 해요 (haeyo, do).

The contractions from lesson 10 are obligatory here too: 와요 (wayo, come), 마셔요 (masyeoyo, drink), 줘요 (jwoyo, give), 돼요 (dwaeyo, become, be OK), 배워요 (baewoyo, learn). Never write *가아요 or *하어요.

요 is a single unstressed syllable written with no space: 먹어요, not *먹어 요.

Step 2 - It works the same for every word class

Korean has no separate “to be” for adjectives, so 동사 (action verbs) and 형용사 (descriptive verbs, lesson 11) run through exactly the same machine. 있다/없다 are regular here as well. Only 이다 is special.

동사 읽다 -> 읽어요 (ilgeoyo, read); 형용사 바쁘다 -> 바빠요 (bappayo, is busy); 있어요 (isseoyo) / 없어요 (eopseoyo); and every noun + 하다 verb inherits 해요 - 공부하다 -> 공부해요 (gongbuhaeyo).

Irregular stems stay irregular in front of 요, because the irregularity happens before the ending is even attached: 덥다 -> 더워요 (deowoyo), 듣다 -> 들어요 (deureoyo), 짓다 -> 지어요 (jieoyo), 모르다 -> 몰라요 (mollayo), 쓰다 -> 써요 (sseoyo). But the regular look-alikes stay regular: 입다 -> 입어요 (ibeoyo), 받다 -> 받아요 (badayo), 웃다 -> 웃어요 (useoyo).

Step 3 - 이다 is the one exception: 이에요 / 예요

The copula does not build a plain 아/어 form. Its 해요체 has its own two shapes, chosen by the 받침 of the noun in front of it, and it attaches to that noun with no space:

Noun with 받침 + 이에요 / Noun ending in a vowel + 예요

• 학생 (받침 ㅇ) -> 학생이에요 (haksaengieyo) - is a student
• 의사 (vowel) -> 의사예요 (uisayeyo) - is a doctor

The negative counterpart is 아니에요 (anieyo), which follows 이/가: 학생이 아니에요 (haksaengi anieyo) - is not a student. Full treatment in lesson 2.

Step 4 - One form, four functions

A 해요체 sentence is ambiguous on paper and perfectly clear in speech. Nothing changes in the ending; the intonation and the context choose the reading.

• Statement - falling intonation: 가요. (Gayo.) - I’m going.
• Question - rising intonation, and in writing a question mark; no word order changes and nothing is added: 가요? (Gayo?) - Are you going?
• Request - a soft imperative, often with 좀 or a gesture: 여기 앉아요. (Yeogi anjayo.) - Sit here. It is gentler than -(으)세요 (lesson 21) but also less deferential, so use it with people at or below your own level.
• Suggestion - marked by 같이 (gachi, together) or 우리 (uri, we): 같이 가요. (Gachi gayo.) - Let’s go together.

This is why Korean questions feel easy at first: there is no auxiliary, no inversion, no do-support.

Step 5 - Where 안 goes

안 is a free adverb standing immediately before the predicate, with a space:

안 + [해요체 predicate]

• 안 가요. (An gayo.) - I’m not going.
• 안 바빠요. (An bappayo.) - I’m not busy.

For noun + 하다 verbs the negative splits the word: 공부 안 해요 (gongbu an haeyo), not *안 공부해요. And 있다 is never negated with 안 - its negative is the separate word 없어요. Everything else about negation is lesson 14.

Step 6 - Why this style, and what the other two are

Korean has several speech levels, but only three are fully alive today. 해요체 is this path’s default because it is the overwhelming majority register of ordinary spoken Korean - and of this project’s own Korean phrase corpus. It is polite enough for shops, colleagues, teachers and strangers, and it is what you will actually hear.

The other two live levels are 합쇼체 (-습니다/-ㅂ니다), the formal deferential style of announcements, news and service speech (lesson 27), and 반말 / 해체, the casual style used with close friends and juniors (lesson 44). Note that 반말 is literally 해요체 minus 요: 해요 -> 해.

Never mix levels inside one sentence or one conversation, and match the pronoun: 저는 … 해요 is polite, 나는 … 해 is casual. *저는 … 해 is a register clash.

Forms & patterns

The ending, chosen by the stem’s last vowel:

Obligatory contractions - never write the long form:

Every word class in 해요체:

The copula’s allomorphs, decided by the 받침:

One form, four functions:

The three living speech levels, same sentence:

Examples

Common mistakes

• 가아요. (Gaayo.) -> 가요. (Gayo.) - When the stem already ends in ㅏ, the ending fuses with it. The uncontracted form is never written.
• 하어요. (Haeoyo.) -> 해요. (Haeyo.) - 하다 does not take -어요. It is the one stem that takes 여, and 하 + 여요 always contracts to 해요.
• 저는 학생이예요. (Jeoneun haksaengiyeyo.) -> 저는 학생이에요. (Jeoneun haksaengieyo.) - 학생 ends in a 받침, so the copula is 이에요. 예요 appears only after a vowel, as in 의사예요.
• 저는 커피를 마셔. (Jeoneun keopireul masyeo.) -> 저는 커피를 마셔요. (Jeoneun keopireul masyeoyo.) - 저는 is the polite pronoun, so the ending must be polite too. Dropping 요 makes it 반말, and 저 + 반말 is a register clash.
• 안 공부해요. (An gongbuhaeyo.) -> 공부 안 해요. (Gongbu an haeyo.) - In a noun + 하다 verb, 안 goes between the noun and 하다, not in front of the whole word.

Tips

• 요 is a switch, not a word. Add it and you are polite; take it off and you are speaking 반말 to a friend. That single syllable is the most useful thing in beginner Korean - when in doubt, keep it on.
• Learn to hear the question, not to build it. There is no inversion and no auxiliary, so 가요 and 가요? are the same two syllables with different pitch. Practise saying every new verb twice, once falling and once rising.
• 해요체 present tense covers more ground than English present. 가요 can mean I go, I’m going, and - with a time word - even I’m going tomorrow. Do not hunt for a progressive form yet; -고 있다 arrives in lesson 32 and is used far less than English -ing.
• Politeness to the listener is not respect for the subject. 해요체 honours the person you are talking to. Honouring the person you are talking about is a separate machine, -(으)시- (lesson 22), and the two stack independently: 가요 (polite) vs 가세요 (polite + honorific subject).