When to use banmal: the polite vs casual dilemma

Korean textbooks usually start with polite 「-아요/어요」 and stay there indefinitely. When learners watch Korean dramas or talk with friends, they discover that nobody speaks exclusively in standard polite forms. Deciding when to switch to casual speech (반말) causes endless anxiety for beginners.

The safe baseline: 해요체 works almost everywhere

As a beginner or intermediate learner, you can use 「해요체」 (-아요/어요) in nearly any daily situation. It is neither stiffly formal nor rude. Native speakers never take offence at a foreign learner speaking standard polite Korean.

There are four primary speech levels you will encounter in real life.

• 합쇼체 (-습니다 / -습니까): Formal polite style used in presentations, news broadcasts, business meetings, and customer service.
• 해요체 (-아요 / -어요): Informal polite style used for the vast majority of everyday conversations with colleagues and acquaintances.
• 해체 (-아 / -어): Casual speech (반말) reserved for close friends, younger siblings, and children.
• 해라체 (-(느)ㄴ다): Plain narrative style. This is primarily a written style for newspapers, books, and essays, not spoken rudeness.

Speech level and honorifics are two different axes

The biggest point of confusion for English speakers is conflating speech level with subject honorifics. Whom you are addressing (the listener) and whom you are talking about (the grammatical subject) are separate choices.

동생이 집에 가요. (Polite style to listener, younger subject)
할머니께서 집에 가세요. (Polite style to listener, honored subject with -(으)시-)

In both sentences, the speaker speaks politely to the listener using 「-요」. The honorific infix 「-(으)시-」 is added only because grandmother is the respected subject. You can even use casual speech with a friend while still respecting your grandmother: 「할머니 주무셔」.

Special honorific vocabulary

Certain frequent Korean verbs change completely when referring to an elder or respected subject.

• 먹다 (eat) becomes 「드시다」 or 「잡수시다」
• 자다 (sleep) becomes 「주무시다」
• 있다 (stay/exist) becomes 「계시다」
• 말하다 (speak) becomes 「말씀하시다」
• 주다 (give) becomes 「드리다」 when offering something to an elder

When is it actually safe to drop honorifics?

Do not assume that casual conversation automatically allows banmal. Switching to banmal requires explicit mutual consent, usually initiated by the older person: 「말 편하게 하세요」 (feel free to speak casually).

Remember the golden rule of Korean etiquette: when uncertain, stay polite. Using honorifics by accident merely sounds slightly formal. Dropping honorifics without permission can ruin a relationship.