Grammar
-다고요
emphatic reported assertion
Form
Declarative quotation form + 요: emphatically repeats or insists on a statement; with a different intonation it can echo a statement in surprise.
Function
Repeats or emphasizes a statement, sometimes correcting the listener or expressing surprise depending on intonation.
Why this form?
-잖아요 — “you know that…”: treats the fact as already known or evident to the listener rather than merely insisting on one's own statement.
How to build it
Present action verb: -ㄴ/는다고요; descriptive adjective: -다고요; noun + 이다: -(이)라고요; past: -았/었다고요. Intonation can turn insistence into a confirmation question.
Forms not to confuse
-잖아요
벌써 늦었잖아요. — You know we're already late.
Examples
도움을 구해야 한다고요!!! — I’m telling you we have to get help!
지금 가야 한다고요! — I'm telling you we have to leave now!