Advanced Temporal: -ㄴ/은/는 즉시 (Immediately Upon)

This grammar acts as a temporal connector. It links two clauses together. The first part is the trigger. The second part is the immediate result. The word 즉시 actually means 'immediately' or 'at once' on its own. By attaching it to a verb, you turn that verb into a starting pistol. The moment the first action finishes, the second one bursts out of the gate. It is like a domino effect. One thing hits, the next thing falls. You will mostly see this used in written Korean. It pops up in news reports, manuals, and business contracts. However, you can definitely use it in speech. It just makes you sound very determined and organized. It's like wearing a suit for your sentences. You aren't just saying what you'll do. You are making a firm promise of speed.

1. 1Creating this pattern is like following a simple recipe. You mostly need the verb stem.
2. 2Find your action verb, like 도착하다 (to arrive).
3. 3Remove the 다 to get the stem: 도착하.
4. 4Add the connector -는 즉시 to the stem.
5. 5You get 도착하는 즉시 (Immediately upon arriving).
6. 6If the action is already finished or you want to emphasize completion, you might see -(으)ㄴ 즉시.
7. 7For stems ending in a vowel: Add -ㄴ 즉시. Example: 가다 -> 간 즉시.
8. 8For stems ending in a consonant: Add -은 즉시. Example: 먹다 -> 먹은 즉시.
9. 9In modern daily use, -는 즉시 is the most common form you will encounter. It works for most situations. It is the safe, 'go-to' choice for your conversations. Just remember to stick to action verbs. This pattern loves movement and tasks. It doesn't play well with adjectives. You wouldn't say 'immediately upon being pretty.' That just sounds silly!

Use this when timing is everything. It is perfect for professional settings. Imagine you are in a job interview. You want to tell them you will start the project right away. You would say, "결과를 받는 즉시 시작하겠습니다" (I will start immediately upon receiving the results). It is also great for health instructions. Doctors might say, "밥을 먹는 즉시 이 약을 드세요" (Take this medicine immediately after eating). Use it when you are giving directions to someone lost. "사거리에 도착하는 즉시 우회전하세요" (Turn right immediately upon arriving at the intersection). It adds a sense of urgency that other patterns lack. Use it when you want to show you are reliable. It tells people they don't have to wait for you. You are on top of things. It’s the linguistic equivalent of a firm handshake.

Don't use this for lazy, casual hangouts. If you are telling a friend you'll call after a nap, -자마자 is better. -는 즉시 can feel a bit too 'intense' for a chill Saturday. Also, avoid using it with adjectives like 'happy' or 'tall.' It is strictly for actions and events. Another 'no-go' zone is when there is a natural delay. If you do something three hours later, this grammar will lie for you. Only use it if the gap between actions is effectively zero. Finally, try not to over-use it in every sentence. It is a powerful spice. If you put it in every dish, it loses its kick. Save it for when you really mean business. Even native speakers save it for moments that require precision. It’s like a grammar tuxedo—don't wear it to the gym.

One big mistake is mixing it up with -자마자. While they are cousins, they aren't twins. -자마자 is friendly and common. -는 즉시 is formal and stiff. Another mistake is using the past tense in the first clause. You don't need to say 도착했는 즉시. The connector already implies the sequence. Just keep the first verb in its base form. Another classic error? Using it for things you can't control. You can't really say 'immediately upon the sun rising' in a casual chat using this. It sounds like you are ordering the sun around! Stick to human actions or planned events. Lastly, watch out for the spelling of 즉시. Don't confuse it with 적시 or other similar-sounding words. Precision is the name of the game here. Yes, even native speakers mess this up when they are typing too fast on KakaoTalk!

Let's compare this to its main rival: -자마자.

• -자마자: Used everywhere. Great for friends, family, and daily life. It's the 'anytime' version of 'as soon as.'
• -는 즉시: The 'business' version. It implies a stronger connection and more formality.

What about -(으)ㄴ 다음에 (after doing)?

• -(으)ㄴ 다음에: This just means 'after.' There could be a 10-minute gap or a 10-year gap.
• -는 즉시: This means 0 seconds later. It is much faster and more urgent.

Think of -자마자 as a casual 'Hey!' and -는 즉시 as a formal 'Greetings.' Both get the job done, but the 'vibe' is totally different. Choosing the right one shows you understand Korean social layers. It makes you look very smart.