🧠 TOEIC Trap: Until vs By — The Deadline vs Duration Test

You see:

Please finish the task ___ Friday.

You spot “Friday,” choose until, and move on.
Then — ❌ — another careless loss.

Why?
Because until and by both talk about time… but mean completely different things.
Under pressure, most test-takers don’t stop to check the logic.

🎯 Why TOEIC Wins This Point

This trap is about endpoint vs deadline.

  • Until = something continues up to that time.
    → I will wait until 6 PM.
    (The waiting lasts the whole time until 6.)

  • By = something is finished any time before or at that time.
    → Please finish the report by Friday.
    (Deadline: before Friday ends.)

TOEIC loves it because:

  • Both seem fine at a glance.

  • “Until” feels softer or more polite — so many pick it without thinking.

💣 The One-Second Trigger

Ask yourself:

“Is this about something continuing, or something finishing?”

  • Continuing → until

  • Finishing → by

👇 Watch It in Action

✅ Correct

She stayed at the office until midnight.
(Action continued until that time) → until

✅ Correct

We must complete the testing phase by next Tuesday.
(Deadline — finish before or on that day) → by

❌ Wrong

Please submit the report until Friday.
(This would mean “keep submitting” until Friday — nonsense) — correct is by.

🧪 TOEIC-Style Practice

The manager asked us to submit the form ___ Friday.
🧠 “Submit” = finish → by

She will be unavailable ___ Thursday due to meetings.
🧠 “Unavailable” = continues → until

We must complete the updates ___ tomorrow afternoon.
🧠 “Complete” = deadline → by

I’ll be here ___ 5 PM if you have any questions.
🧠 “Be here” = continues → until

📝 Your Turn

Fill each blank with until or by.
Use the one-second check: continuing → until / finishing → by.

  1. The team needs to finish the update ___ tomorrow afternoon.

  2. She will be unavailable ___ Thursday.

  3. Please complete the registration process ___ Monday at 10 AM.

  4. I’ll stay here ___ the technician arrives.

Answer Key + Coaching

  1. ✅ by — “finish” = deadline

  2. ✅ until — “unavailable” = continues

  3. ✅ by — “complete” = deadline

  4. ✅ until — “stay” = continues

🔁 Takeaway Rule

Don’t pick what feels polite — pick what matches the time logic.

  • Deadline → by

  • Duration → until

If it’s about finishing before a time, it’s by.
If it’s about something lasting up to a time, it’s until.

Final Word

This is a logic trap, not a vocabulary test.
See the time clue, match the logic, and take the point.

For more strategies and resources to master TOEIC time traps, visit the English Library Collection and start locking in time-clue confidence today.

FAQ (English) — Until vs By (No numbering, UTF-8 clean, formatted for SEO + chatbot) What is the difference between “until” and “by” in TOEIC questions “Until” means something continues up to a point in time. “By” means something is finished before or at that time. When should I use “by” instead of “until” in TOEIC grammar Use “by” when the sentence is about a deadline or goal — something that must be completed before or at a specific time. Why is “until” the wrong choice in deadline questions “Until” suggests ongoing action. For deadlines, you need “by” to show completion. How do I know if TOEIC wants “until” or “by” Ask: is the action continuing (use “until”) or finishing (use “by”)? That’s the key test. Is “by” used for future deadlines on TOEIC Yes. “By” is the standard preposition to mark future deadlines in TOEIC questions. Does “until” mean the same as “before” No. “Until” shows something continues up to a time. “Before” and “by” show when something is done. What does “by Friday” really mean on TOEIC It means the action should be completed any time before or on Friday — not after. Can “until” be used in TOEIC Part 5 questions Yes, but only when the verb shows a continuous action like “wait,” “stay,” or “work.” Is “until” ever correct in TOEIC deadline questions Rarely. “Until” only fits if the sentence is about continuing, not finishing. What is the grammar logic behind “until” and “by” “Until” = continuous action. “By” = finished action. TOEIC tests this subtle difference often. What kind of verbs follow “by” in TOEIC traps Verbs like “complete,” “submit,” “finish,” “respond,” or “send” often go with “by” in deadlines. How does TOEIC test time prepositions like “by” and “until” TOEIC puts both as answer choices and hides the trap in the logic of the verb. Does “stay until” mean the same as “stay by” No. “Stay until” is correct. “Stay by” is incorrect and unnatural. Can I use “by” when something continues up to a time No. Use “until” when describing something that keeps going up to a certain point. Why do I keep getting “by” vs “until” questions wrong Most people follow feeling, not logic. These questions test meaning, not memory. What is the difference between “stay until” and “leave by” “Stay until” means you are present up to that time. “Leave by” means you are gone before or at that time. Are “until” and “by” tested in TOEIC Part 6 fill-in-the-blank Yes. TOEIC often uses short time-based sentences to test this difference under time pressure. What’s the trick for choosing between “until” and “by” Check if the sentence is about continuing (until) or completing (by). That’s the only thing that matters. How can I practice the “until” vs “by” question type Review real TOEIC-style questions where the action verb tells you the right preposition. Which one is correct: submit until Friday or submit by Friday “Submit by Friday” is correct. “Submit until Friday” is incorrect because “submit” is a completed action.
A colour image of a room full of people taking the TOEIC test in the room.