Until vs By: Choose by Continuing Time or Deadline
In TOEIC Part 5, until and by often appear in sentences about deadlines, office hours, submissions, deliveries, meetings, and service availability.
The fast choice is not “Can I explain the grammar?” The fast choice is: does the sentence show something continuing, or does it show a deadline?
The 7-second choice
Do not translate the sentence first. Look at the action around the time expression.
Until
Use it when something continues up to a time: open until 6 p.m., available until Friday, wait until the manager returns.
By
Use it when something must be finished no later than a time: submit by Monday, arrive by 3 p.m., complete by the deadline.
The signal to remember
This is the MTC move. Do not name the grammar. Check whether the action continues or must be completed.
The office stays open up to that time. Choose until.
The report must be submitted no later than that time. Choose by.
The discount continues up to that point. Choose until.
The applications must arrive before the limit. Choose by.
What TOEIC wants you to notice
TOEIC often uses this trap in business sentences about offices, stores, delivery schedules, application forms, reports, payment dates, meetings, and service periods.
The trap is that both choices connect to time. But TOEIC is checking whether the time is a continuing period or a deadline.
Something continues up to a time. Choose until.
The condition continues up to a time. Choose until.
Something must be completed no later than a time. Choose by.
The time is a deadline. Choose by.
Watch the small words
The action near the blank usually makes the decision clear.
Choose until
Look for continuing states: open, available, valid, closed, postponed, wait, remain, stay.
Choose by
Look for completion actions: submit, finish, complete, receive, return, pay, arrive, send.
This is not about explaining the sentence. It is about seeing whether the time shows continuation or a completion limit.
Quick TOEIC check
Choose first. Then read the feedback. Use the one-second check: continuing time, or deadline?
1. The customer service desk will be open ___ 8 p.m.
2. Please submit the completed form ___ 8 p.m.
3. The special offer is valid ___ Friday.
4. All invoices must be paid ___ Friday.
The mistake fast readers make
Fast readers often see a time expression and choose by translation. TOEIC uses that as the trap.
Weak choice
Choose because both choices seem connected to time.
Better choice
Check the action. Does it continue, or must it be finished?
This is the MTC move: avoid the grammar maze, find the signal, make the decision, and move on.
Why this mistake returns under pressure
Many test-takers know until and by during review, but still miss them in timed practice. The problem is often not the meaning alone. It is the speed of the signal check.
Under pressure, use the same move every time: look at the action around the time and ask whether it continues or must be completed.
Use small TOEIC mistakes as a diagnostic
If you know the answer after review but miss it during timed practice, the problem may not be the word alone. It may be your decision pattern.
Start with the Learning Block Diagnostic to see whether your mistakes connect to Speed Trap, Memoriser, Over Thinker, Translator, Passive Listener, or Burnout.
Continue reading
Use these pages to turn small TOEIC mistakes into faster decisions and better review.