Korean Have to Grammar: Patterns, Rules and Examples

What Are the Korean Have to Grammar Patterns?

Korean have to grammar means the sentence endings that talk about duty, permission and prohibition. A sentence ending is the last part of a Korean sentence, after the verb stem. It tells the listener how to take the sentence: as a duty, as a permission or as a rule. This set belongs to the wider group of Korean sentence endings, inside the Korean Grammar hub.

Korean builds these meanings from small pieces. Many patterns end in 되다, which means "to be acceptable." The piece before it changes the meaning. Compare three sentences that use the same verb, 먹다 ("to eat"):

• 먹어야 해요 means "You have to eat."
• 먹어도 돼요 means "You may eat."
• 먹으면 안 돼요 means "You must not eat."

Only the middle piece changes (야, 도 or 으면 안), and the meaning goes from duty to permission to ban. Once you see that, the whole set becomes easier to organise. The lessons below teach each piece with examples, audio and practice.

Which Pattern Should You Learn First?

Learn -아/어야 하다/되다 first, because "I have to..." is the most useful sentence in daily talk. Next learn -아/어도 되다, which lets you ask permission, and -(으)면 안 되다, which lets you understand rules. These three cover most situations at A2.

A good starter order is:

1. -아/어야 하다/되다 (must, have to).
2. -아/어도 되다 (may, it's okay to).
3. -(으)면 안 되다 (must not, may not).
4. -지 않아도 되다 (don't have to) and -(으)면 되다 (all you need to do is).
5. The intermediate patterns, then the advanced pair.

The level of each pattern is an editorial estimate. It places 5 patterns at A2, 2 at B1 and 2 at B2, and it maps them to TOPIK I and II. Use the levels as a guide, not as a rule. Use the quick chooser below when you know the meaning you want but not the pattern.

Two B2 lessons complete the set: -지 않으면 안 되다 (have to, double negative) and -지 않을 수 없다 (cannot help but).

The Patterns, Grouped by Level

The patterns below are grouped by level. Each entry gives a one-line snippet and one example. Open the lesson for the formation rule, the irregular stems, the audio and the practice set.

Beginner Patterns (A2)

• -아/어야 하다/되다 (must, have to). The standard way to state a duty. Add -아/어야 to the stem and finish with 해요 or 돼요: 내일 일찍 일어나야 해요 (naeil iljjik ireonaya haeyo) = "I have to get up early tomorrow."
• -아/어도 되다 (may, it's okay to). Gives or asks for permission: 여기에서 사진을 찍어도 돼요? (yeogieseo sajineul jjigeodo dwaeyo?) = "May I take photos here?"
• -(으)면 안 되다 (must not, may not). The everyday prohibition, and the negative counterpart of -아/어도 되다: 여기에서 담배를 피우면 안 돼요 (yeogieseo dambaereul piumyeon an dwaeyo) = "You must not smoke here."
• -(으)면 되다 (all you need to do is). Names the one thing that is enough: 이 버튼을 누르면 돼요 (i beoteuneul nureumyeon dwaeyo) = "You just press this button."
• -지 않아도 되다 (don't have to). Cancels a duty without forbidding anything: 내일은 일찍 오지 않아도 돼요 (naeireun iljjik oji anado dwaeyo) = "You don't have to come early tomorrow."

Intermediate and Advanced Patterns (B1 and B2)

• -(으)ㄹ 필요가 있다/없다 (need to / no need to). A calmer and more formal way to state necessity, common in advice and reports: 걱정할 필요 없어요 (geokjeonghal piryo eopseoyo) = "There is no need to worry."
• -아/어서는 안 되다 (must not). A firm and formal ban for signs, rules and moral statements: 약속을 어겨서는 안 돼요 (yaksogeul eogyeoseoneun an dwaeyo) = "You must not break a promise."
• -지 않으면 안 되다 (have to). A strong "must" built from two negatives, stronger than -아/어야 하다: 가지 않으면 안 돼요 (gaji aneumyeon an dwaeyo) = "I have to go."
• -지 않을 수 없다 (cannot help but). A double negative for an action that circumstances or feelings make unavoidable: 웃지 않을 수 없었어요 (utji aneul su eopseosseoyo) = "I could not help laughing."

Notice that -아/어야 하다 and -지 않을 수 없다 both describe things that must happen, but they differ sharply. The first states a duty that someone imposes or feels: 가야 해요 ("I have to go"). The second describes an unavoidable reaction: 웃지 않을 수 없어요 ("I cannot help laughing"). Learn the first pattern before the second, because the second builds on the long negative -지 않다 and on -(으)ㄹ 수 없다 ("cannot"), which need more grammar behind them.

How Do You Choose between Look-Alike Patterns?

Choose by the question each pattern answers. Four short rules solve most cases:

• Duty or permission? Ending in 야 means you have to. Ending in 도 means you may. 가야 해요 and 가도 돼요 differ by only one syllable, so check the middle sound.
• Ban or "enough"? Both -(으)면 안 되다 and -(으)면 되다 share -(으)면, and only 안 separates "must not" from "all you need to do is." 먹으면 안 돼요 is a ban, and 먹으면 돼요 means "Eating is enough."
• Cancel or forbid? -지 않아도 되다 releases someone from a duty, and -(으)면 안 되다 restricts them. 가지 않아도 돼요 means "You don't have to go," and 가면 안 돼요 means "You must not go."
• Calm or firm? -(으)ㄹ 필요가 있다 gives advice, and -아/어야 하다 states a duty. In the same way, -(으)면 안 되다 is the everyday ban and -아/어서는 안 되다 is the firm one.

Two comparison pages go deeper. -아/어도 되다 vs -(으)면 되다 separates "may" from "all you need to do is," and -아/어야 하다 vs -(으)ㄹ 필요가 있다 separates a direct duty from a formal need. The pair that learners trip on most is the refusal: the answer to "May I?" in the negative is -(으)면 안 돼요, not -아/어도 안 돼요.

Where Can You Practise?

Practise by moving from recognition to production. First read a lesson and listen to the audio on each example. Then do the practice set at the end of the lesson. Last, write your own sentences about your day: three duties, three permissions and three bans.

1. Read the lessons in the starter order above. Each one ends with a practice set and answer key.
2. Say each example aloud after the audio, and check the sounds that change, such as 앉아도 [안자도] and 약을 먹어야 [야글 머거야].
3. Write a short note to a friend that uses at least one duty, one permission and one ban.
4. For a wider view, use the Beginner Grammar list for the A2 patterns, or the Intermediate Grammar list for the B1 and B2 patterns.

Remember that all of these patterns end with a word that carries the speech level. 해요 and 돼요 are polite. 합니다 and 됩니다 are formal. 해 and 돼 are casual. The part before the last word never changes, so you only need to learn each pattern once.

What Does This Section Not Cover?

This section covers sentence endings for duty, permission and prohibition. It does not cover patterns for ability, desire, suggestion or guessing, and it does not teach basic grammar parts that other hubs explain. Related topics live elsewhere:

• Ability and possibility, such as -(으)ㄹ 수 있다: Ability and Possibility.
• The long negative and commands not to do something: Korean negation.
• Particles, tenses and speech levels: Korean particles, Korean tenses and speech levels.
• Connectors such as -(으)면 ("if"): Korean connectors.
• Modifiers and auxiliary verbs: Korean modifiers and auxiliary verbs.

Start with -아/어야 하다/되다 if you are unsure where to begin.

Frequently Asked Questions

How do Korean "must", "may" and "must not" differ?

The difference sits in the small piece before 되다 or 하다. The ending -아/어야 하다/되다 ("must") states a duty, -아/어도 되다 ("may") gives permission and -(으)면 안 되다 ("must not") bans an action. 먹어야 해요, 먹어도 돼요 and 먹으면 안 돼요 show all three with one verb. The set adds -(으)면 되다 ("all you need to do is"), -지 않아도 되다 ("don't have to") and four patterns for need and formal rules.

Which pattern should I learn first?

Learn -아/어야 하다/되다 first, because "I have to..." is the most useful sentence in daily talk. Then learn -아/어도 되다 for permission and -(으)면 안 되다 for prohibition. Those three cover most situations. After that, add -지 않아도 되다, -(으)면 되다 and the formal patterns. The two B2 patterns can wait until you read longer texts.

How do I know which pattern fits my sentence?

Ask what you want to say. For a duty, use -아/어야 해요. For permission, use -아/어도 돼요. For a ban, use -(으)면 안 돼요. For "just do this," use -(으)면 돼요. For "you needn't," use -지 않아도 돼요. The quick chooser table on this page lists each meaning with its pattern, its level and an example sentence.

Are these patterns on the TOPIK exam?

The common patterns, such as -아/어야 하다, -아/어도 되다 and -(으)면 안 되다, appear in grammar lists for TOPIK I and early TOPIK II study. The more formal patterns, such as -아/어서는 안 되다 and -지 않을 수 없다, are more typical of TOPIK II reading and writing. The levels on this site are editorial estimates, so check them against your current syllabus.

Where are the comparison pages?

Two comparison pages cover the most confusing pairs. One compares -아/어도 되다 ("may") with -(으)면 되다 ("all you need to do is"), and the other compares -아/어야 하다 ("must") with -(으)ㄹ 필요가 있다 ("need to"). Both are linked from the how-to-choose section on this page and from the lessons that they compare.