Grammar
-(으)ㄴ/는 셈이다
Meaning
Advanced-(eu)n/neun semida
Closes a passage by stating what the facts just given add up to — 'it amounts to ~', 'in effect ~'. It introduces no new information; it tells the reader how to total up the information already on the page, which is why it earns its place when the headline figure and the underlying situation point in different directions. 셈 is the noun for a reckoning or a count, and that is the work the phrase does.
Form
셈 is a bound noun, so the clause in front takes a modifier ending and a space: -(으)ㄴ 셈이다 for a completed action (줄어들다 → 줄어든 셈이다, 커지다 → 커진 셈이다) or a descriptive verb (싸다 → 싼 셈이다), and -는 셈이다 for something ongoing (오르다 → 오르는 셈이다). A stem ending in ㄹ drops it before ㄴ (만들다 → 만든 셈이다). With a noun the form is N인 셈이다. 이다 then carries the tense and politeness at the end (셈입니다, 셈이었다).
Examples
물가가 오르면 월급이 그대로여도 소득이 줄어든 셈입니다.
If prices go up, your income has effectively fallen even when your salary stays the same.
Common mistakes & nuance
Do not read -(으)ㄹ 셈이다 as the future of this pattern — it is a different point meaning 'intend to', usually with a suspicious edge (어쩔 셈입니까, 'what are you planning to do?'). Only the -(으)ㄴ and -는 shapes mean 'amounts to'. The other thing to keep in mind is that 셈이다 is a judgement, not a report: on a figure that simply is what it is, it adds nothing, and the sentence is better off plain.
Similar grammar
- -(으)ㄴ/는 것
In its -(으)ㄴ/는 것입니다 shape, this restates the fact just given in other words — 'what happened is that ~'. -(으)ㄴ/는 셈이다 does not restate; it totals up, and the total can differ from any single figure that was stated (전체 물가는 둔화됐지만 압력은 커진 셈입니다).
- -(으)로 풀이되다/분석되다
Both mark a line as a reading rather than a raw fact, but they differ in whose reading it is. 풀이되다/분석되다 hands the interpretation to unnamed analysts; -(으)ㄴ/는 셈이다 is the writer doing the arithmetic in front of the reader, out of figures already given.