Must / Have To in Korean — -아/어야 되다 and Obligations

<h2>Duty in Korea — Much More Than a Grammar Rule</h2> <p>In Korea, the concept of duty goes far beyond grammar. The notion of 의무 (uimu — obligation) is deeply rooted in the culture. When I started working at a Korean company twelve years ago, I quickly understood that "해야 돼요" (haeya dwaeyo — you have to do it) was the most frequently spoken phrase in the office. Meeting at 7 AM? 가야 돼요 (have to go). Company dinner until midnight? 참석해야 돼요 (have to attend). In Korea, duty is a way of life.</p> <h2>The Main Structure: -아/어야 되다/하다 — "Must / Have To"</h2> <p>To express obligation, use the verb stem + <strong>-아/어야 되다</strong> (or -아/어야 하다, which is identical).</p> <h3>[Conjugation](/en/blog/korean-conjugation-is-simpler-than-french-conjugation-here-s-why) Rule</h3> <table> <tr><th>Last vowel of stem</th><th>Addition</th><th>Example</th></tr> <tr><td>ㅏ or ㅗ</td><td>-아야 되다</td><td>가다 → 가야 되다</td></tr> <tr><td>Other vowels</td><td>-어야 되다</td><td>먹다 → 먹어야 되다</td></tr> <tr><td>하다</td><td>-해야 되다</td><td>공부하다 → 공부해야 되다</td></tr> </table> <h3>Conjugated Examples (Polite Form)</h3> <table> <tr><th>Verb</th><th>Obligation</th><th>Romanization</th><th>Translation</th></tr> <tr><td>[가다](/en/dictionary/%EA%B0%80%EB%8B%A4) (to go)</td><td>가야 돼요</td><td>gaya dwaeyo</td><td>I have to go</td></tr> <tr><td>먹다 (to eat)</td><td>먹어야 돼요</td><td>meoeoya dwaeyo</td><td>I have to eat</td></tr> <tr><td>공부하다 (to study)</td><td>공부해야 돼요</td><td>gongbuhaeya dwaeyo</td><td>I have to study</td></tr> <tr><td>자다 (to sleep)</td><td>자야 돼요</td><td>jaya dwaeyo</td><td>I have to sleep</td></tr> <tr><td>일하다 (to work)</td><td>일해야 돼요</td><td>ilhaeya dwaeyo</td><td>I have to work</td></tr> <tr><td>만나다 (to meet)</td><td>만나야 돼요</td><td>mannaya dwaeyo</td><td>I have to meet</td></tr> <tr><td>읽다 (to read)</td><td>읽어야 돼요</td><td>ilgeoya dwaeyo</td><td>I have to read</td></tr> </table> <h3>되다 vs 하다 — What's the Difference?</h3> <p>You'll see both forms: -아/어야 <strong>되다</strong> and -아/어야 <strong>하다</strong>. The difference is subtle:</p> <table> <tr><th>-아/어야 되다</th><th>-아/어야 하다</th></tr> <tr><td>More conversational</td><td>More formal, more written</td></tr> <tr><td>"You need to..."</td><td>"One must..."</td></tr> <tr><td>가야 돼요</td><td>가야 해요</td></tr> </table> <p>In everyday life in Seoul, I use -아/어야 돼요 about 90% of the time. The 하다 form comes out mainly in professional contexts or presentations.</p> <h2>Real-Life Examples in Seoul</h2> <p>Here are sentences you'll constantly hear (or say) in Korea:</p> <ul> <li><strong>내일 일찍 일어나야 돼요</strong> (naeil iljjik ireonaya dwaeyo) — I have to wake up early tomorrow</li> <li><strong>한국어를 더 열심히 공부해야 돼요</strong> (hangugeo-reul deo yeolsimhi gongbuhaeya dwaeyo) — I need to study Korean harder</li> <li><strong>비자를 갱신해야 돼요</strong> (bijareul gaengsinhaeya dwaeyo) — I have to renew my visa</li> <li><strong>세금을 내야 돼요</strong> (segumeul naeya dwaeyo) — I have to pay taxes</li> <li><strong>병원에 가야 돼요</strong> (byeongwon-e gaya dwaeyo) — I have to go to the hospital</li> </ul> <p>The visa sentence — I've said it so many times in twelve years... Visa renewal in Korea is an annual ritual involving hours of waiting at the immigration office (출입국관리사무소). Every time, I think "다시 가야 돼요..." (have to go again...).</p> <h2>The Negative: "Don't Have To" / "Must Not"</h2> <h3>-지 않아도 되다 — "Don't Need To"</h3> <p>To say something is NOT necessary:</p> <table> <tr><th>Obligation</th><th>No obligation</th><th>Translation</th></tr> <tr><td>가야 돼요</td><td>가지 않아도 돼요</td><td>Don't need to go</td></tr> <tr><td>먹어야 돼요</td><td>먹지 않아도 돼요</td><td>Don't need to eat</td></tr> <tr><td>공부해야 돼요</td><td>공부하지 않아도 돼요</td><td>Don't need to study</td></tr> </table> <p>Very common short form: <strong>안 -아/어도 돼요</strong></p> <ul> <li>안 가도 돼요 (an gado dwaeyo) — Don't need to go</li> <li>안 먹어도 돼요 (an meoeodo dwaeyo) — Don't need to eat</li> </ul> <h3>-(으)면 안 되다 — "Must Not" (Prohibition)</h3> <p>Be careful, this is different! -(으)면 안 되다 expresses a <strong>prohibition</strong>, not simply the absence of obligation.</p> <table> <tr><th>Expression</th><th>Example</th><th>Translation</th></tr> <tr><td>-(으)면 안 되다</td><td>거짓말하면 안 돼요</td><td>You must not lie</td></tr> <tr><td></td><td>늦으면 안 돼요</td><td>You must not be late</td></tr> <tr><td></td><td>여기서 뛰면 안 돼요</td><td>You must not run here</td></tr> <tr><td></td><td>술을 마시면 안 돼요</td><td>You must not drink alcohol</td></tr> </table> <p>Crucial comparison:</p> <ul> <li><strong>안 가도 돼요</strong> — Don't need to go (it's optional)</li> <li><strong>가면 안 돼요</strong> — Must NOT go (it's forbidden)</li> </ul> <h2>Levels of Obligation in Korean</h2> <p>From weakest to strongest:</p> <table> <tr><th>Level</th><th>Expression</th><th>Example</th><th>Translation</th></tr> <tr><td>Light suggestion</td><td>-(으)면 좋겠다</td><td>가면 좋겠어요</td><td>It would be nice to go</td></tr> <tr><td>Advice</td><td>-는 게 좋다</td><td>가는 게 좋아요</td><td>It's better to go</td></tr> <tr><td>Soft obligation</td><td>-아/어야 되다</td><td>가야 돼요</td><td>You have to go</td></tr> <tr><td>Strong obligation</td><td>반드시 -아/어야 하다</td><td>반드시 가야 해요</td><td>You absolutely must go</td></tr> <tr><td>Command</td><td>-(으)세요</td><td>가세요</td><td>Go (polite imperative)</td></tr> </table> <h2>Duty in Korean Culture</h2> <p>In Korea, social obligations are particularly strong. Here are some cultural "duties" I discovered living here:</p> <ul> <li><strong>어른한테 존댓말을 써야 돼요</strong> — You must use respectful language with elders</li> <li><strong>설날에 부모님을 찾아가야 돼요</strong> — You must visit your parents for Lunar New Year</li> <li><strong>회식에 참석해야 돼요</strong> — You must attend company dinners</li> <li><strong>어른이 먼저 먹어야 돼요</strong> — Elders must eat first</li> </ul> <p>The concept of 눈치 ([nunchi](/en/blog/the-concept-of-nunchi-korean-social-intelligence-explained) — reading the atmosphere) is also part of "duty" in Korea. You need to read situations and act accordingly. After twelve years, my 눈치 has improved considerably, but I still make blunders sometimes!</p> <h2>Useful Expressions with Obligation</h2> <ul> <li><strong>지금 가야 돼요, [미안해요](/en/korean/how-to-say-sorry-in-korean)</strong> (jigeum gaya dwaeyo, mianhaeyo) — I have to go now, sorry</li> <li><strong>뭐 해야 돼요?</strong> (mwo haeya dwaeyo?) — What do I have to do?</li> <li><strong>언제까지 해야 돼요?</strong> (eonjekkaji haeya dwaeyo?) — By when do I have to do it?</li> <li><strong>꼭 해야 돼요?</strong> (kkok haeya dwaeyo?) — Do I really have to?</li> </ul> <h2>Summary</h2> <table> <tr><th>Expression</th><th>Meaning</th><th>Register</th></tr> <tr><td>-아/어야 되다</td><td>Must / have to</td><td>Conversational</td></tr> <tr><td>-아/어야 하다</td><td>Must / have to</td><td>Formal</td></tr> <tr><td>-지 않아도 되다</td><td>Don't have to</td><td>All registers</td></tr> <tr><td>-(으)면 안 되다</td><td>Must not (forbidden)</td><td>All registers</td></tr> </table> <p>Ready to master obligations in Korean? <a href="/en/signup">Sign up on Seonsaengnim</a> and [learn Korean](/en/korean) grammar with practical exercises and real-life scenarios.</p>