A single spelling error in an email or report can shake your reader's confidence — no matter how solid the content is. The moment someone notices the mistake, an unconscious impression forms: "this person isn't careful."

What makes these errors particularly tricky is that they don't come from poor language ability. They come from years of exposure to incorrect forms. The expressions you use most often are the ones you're most likely to get wrong. The 7 patterns below are the ones Korean office workers repeat most.

Mistake 1 — "안 됩니다" vs "않습니다"

The most common error. The rule is straightforward.

Expression	Correct Usage	Example
안 됩니다	Contraction of "아니+되다" — something is not allowed or not possible.	"이 방향으로는 안 됩니다." (This direction won't work.)
않습니다	Contraction of "아니하다" — negating a verb or adjective.	"그렇게 생각하지 않습니다." (I don't think so.)

Quick check: if you can substitute "아니하다" and the sentence still makes sense, use "않다." If it doesn't, use "안 되다."

Wrong: "이 방향으로는 않습니다." (X) → Correct: "이 방향으로는 안 됩니다." (O)

Mistake 2 — "~로서" vs "~로써"

Both appear constantly in business documents, and the two get mixed up all the time.

Particle	Usage	Example
~로서	Capacity, status, or role	"팀장으로서 책임을 지겠습니다." (As team lead, I'll take responsibility.)
~로써	Means, tool, or material	"데이터로써 근거를 제시합니다." (I'll present evidence through data.)

Tip: try replacing "~으로" with "~을 통해서." If the sentence still works, use "로써." If not, use "로서."

Mistake 3 — "~에요" vs "~예요"

Used constantly at the end of emails and messages — and surprisingly often wrong.

Form	Rule	Example
~예요	After words ending in a vowel before "이다"	"저예요.", "회의예요."
~이에요	After words ending in a consonant before "이다"	"김 팀장이에요.", "내일이에요."

Wrong: "내일 회의에요." (X) → Correct: "내일 회의예요." (O)

Mistake 4 — "왠지" vs "웬지"

Common in both spoken conversation and written messages — and regularly misspelled.

The answer is always "왠지". It's a contraction of "왜인지" (for some reason). "웬지" simply doesn't exist in Korean.

Note: "웬" does exist on its own, as in "웬 말이야?" or "웬 일이야?" — here "웬" means "what kind of." That's a different word entirely.

Wrong: "웬지 불안하네요." (X) → Correct: "왠지 불안하네요." (O)

Mistake 5 — "됬어요" vs "됐어요"

"됐어요" and "됩니다" come up constantly, yet many people spell them wrong.

"됐어요" is a contraction of "되었어요." "됬어요" is not a real word. The breakdown: 되 + 었 + 어요 = 됐어요.

Wrong	Correct
됬습니다	됐습니다
됬어요	됐어요
안됬어요	안 됐어요

Mistake 6 — "~할게요" vs "~할께요"

Common at the close of emails: "확인할게요" (I'll check), "연락드릴게요" (I'll be in touch).

The correct form is always "~할게요". The tensed consonant form "께" is not used here. This applies across the board: "할게요", "드릴게요", "보낼게요."

Wrong: "검토 후 연락드릴께요." (X) → Correct: "검토 후 연락드릴게요." (O)

Mistake 7 — Spacing: "할 수 있다" vs "할수있다"

Bound nouns and auxiliary verbs must be written with a space. This is one of the most frequent Korean orthography errors overall.

Wrong	Correct	Rule
할수있다	할 수 있다	"수" is a bound noun — space required
알아봐야할것같다	알아봐야 할 것 같다	"것" and "같다" both need spaces
확인해야할것같습니다	확인해야 할 것 같습니다	Space before auxiliary verbs
검토해보겠습니다	검토해 보겠습니다	Auxiliary verbs are principally spaced separately

Some auxiliary verb combinations are permissible without a space, which makes this one confusing. When in doubt, adding the space is closer to the standard rule.

One at a Time

Trying to fix all seven at once usually results in fixing none. This week, focus only on "안 됩니다 / 않습니다" until it's automatic. Next week, move to "~로서 / ~로써." Building one correction at a time is what actually works.

Grammar is a habit, not just knowledge. A wrong pattern that's been used for years won't disappear overnight — but with conscious practice, it usually corrects itself within a few weeks.