Common Mistakes with Không and Chưa | Vietnamese Grammar

English uses not, didn't, and haven't across situations that Vietnamese divides according to the speaker's view of the event. Không gives a neutral denial: the action, habit, intention, or property does not hold. Chưa places a boundary at “now” or another reference time and says that an expected or relevant development has not happened up to that boundary. The repair is therefore not “translate not yet as chưa every time”; it is “decide whether the proposition is closed or still pending.”

This page diagnoses that choice. It leaves possession and existence with có / không có to Common Mistakes with Có and Không Có.

The core contrast: denied or still pending?

Compare two fully grammatical sentences:

Tôi không ăn sáng.

I don't eat breakfast / I am not having breakfast.

Tôi chưa ăn sáng.

I haven't eaten breakfast yet.

The first can describe a habit, refusal, or plan. The second presents breakfast as a relevant event whose completion remains open. Using không where chưa is intended is not necessarily ungrammatical; it can communicate the wrong decision about the future.

💡

Ask what happens after the reference time. If the speaker leaves open a later change, chưa is likely. If the speaker merely rejects the proposition, use không.

Diagnostic	Choose không	Choose chưa
Habit or stable preference?	không uống rượu	—
Event incomplete by now?	—	chưa gửi thư
Target state not reached?	—	phòng chưa sạch
Neutral negative property?	phòng không rộng	—
Past event simply did not occur?	hôm qua không đi	—
Event pending at a past/future boundary?	—	lúc đó chưa đến

Chưa is about a reference boundary, not an English tense

English speakers often equate chưa with the present perfect because “haven't ... yet” is a common translation. That shortcut fails when the reference time is past or future.

Khi chúng tôi tới, cửa hàng vẫn chưa mở.

When we arrived, the shop still had not opened.

Nếu đến chín giờ mà chị chưa gọi, tôi sẽ về trước.

If you haven't called by nine, I'll go home first.

In the first sentence, chưa looks back from the time of arrival. In the second, it looks back from a future nine-o'clock deadline. No Vietnamese verb changes tense. The surrounding clause supplies the boundary.

By contrast, a completed time period can favor không when there is no remaining expectation:

Hôm qua anh ấy không đến cuộc họp.

He didn't come to the meeting yesterday.

The meeting is over; the speaker simply denies attendance. Hôm qua anh ấy chưa đến cuộc họp would require a past viewpoint at which his arrival was still pending, normally followed by more context: Đến chín giờ hôm qua anh ấy vẫn chưa đến “By nine yesterday, he still hadn't arrived.”

With adjectives and states, chưa treats a standard or stage as not reached. Không merely denies the property.

Bản báo cáo này không rõ.

This report is unclear.

Bản báo cáo này chưa rõ; cần thêm hai ví dụ.

This report isn't clear enough yet; it needs two more examples.

The second sentence projects a repairable target. The same implication can be delicate with life stages:

Anh Nam không có con.

Nam does not have children.

Anh Nam chưa có con.

Nam does not have children yet.

Both are grammatical. Chưa có con frames parenthood as an anticipated later development, which may be intrusive or inaccurate. In neutral conversation, do not choose chưa merely because English permits “not yet.”

Statements, questions, and answers use different positions

Preverbal chưa negates a pending predicate: Tôi chưa ăn. Final chưa in a completion question asks whether the boundary has been crossed: Bạn ăn chưa? “Have you eaten yet?” It is not the same slot as the negator.

— Bạn ăn chưa? — Chưa, tôi đang đợi Linh.

— Have you eaten yet? — Not yet; I'm waiting for Linh.

Compare a general polar question:

— Bạn có ăn thịt không? — Không, tôi ăn chay.

— Do you eat meat? — No, I'm vegetarian.

The natural negative answer follows the question's semantic axis: chưa for incomplete-by-now, không for an ordinary positive-versus-negative choice. For more detail, see Đã...Chưa Questions.

A six-repair self-editing drill

Each left-hand sentence reflects a real English transfer. Some are structurally possible Vietnamese but produce a different interpretation.

English intention	Misdiagnosis	Repair	Why
I haven't eaten yet.	Tôi không ăn.	Tôi chưa ăn.	The meal remains pending.
I don't eat meat.	Tôi chưa ăn thịt.	Tôi không ăn thịt.	This is a stable practice, not a temporary gap.
The bus hasn't arrived yet.	Xe buýt không đến.	Xe buýt chưa đến.	Arrival is expected.
I didn't go yesterday.	Hôm qua tôi chưa đi.	Hôm qua tôi không đi.	The finished day supplies a closed denial.
The rice isn't cooked yet.	Cơm không chín.	Cơm chưa chín.	Cooking has not reached its endpoint.
I don't know how to drive.	Tôi chưa biết lái xe.	Tôi không biết lái xe.	Use không unless future learning is genuinely implied.

⚠️ Xe buýt không đến.

Grammatical, but wrong for the intended ‘The bus hasn't arrived yet’; this can mean the bus is not coming.

✅ Xe buýt chưa đến.

The bus hasn't arrived yet.

⚠️ Tôi chưa ăn thịt.

Grammatical, but wrong for the intended ‘I don't eat meat’; this suggests that eating meat remains possible later.

✅ Tôi không ăn thịt.

I don't eat meat.

Dialogue repair: answer the question that was asked

Mai: Cậu gửi bản hợp đồng chưa? — Duy: Không.

Mai: Have you sent the contract yet? — Duy: No. (understandable, but the answer fails to preserve the completion frame)

Mai: Cậu gửi bản hợp đồng chưa? — Duy: Chưa, tớ đang sửa trang cuối. Trước năm giờ tớ sẽ gửi.

Mai: Have you sent the contract yet? — Duy: Not yet; I'm editing the last page. I'll send it before five.

The repair chooses chưa, then confirms the pending interpretation with đang sửa and a future deadline. A bare không can sound like a refusal to send rather than a report that sending is incomplete.

Register and regional reach

Both không and chưa are neutral and standard across Vietnamese regions. In casual speech, pronunciation of không and the choice of expressive alternatives can vary, but standard writing preserves không. Chả/chẳng can strengthen or color a denial (informal; chả is especially frequent in Northern conversation), yet neither is a replacement for the not-yet meaning of chưa. In formal reporting, make the reference point explicit—đến thời điểm kiểm tra vẫn chưa... “as of the inspection, still not...” — when chronology matters.

Common Mistakes

1. Translating every English perfect negative with chưa

⚠️ Năm ngoái tôi chưa tham dự hội nghị đó.

Possible with a past pending viewpoint, but wrong if the intended fact is simply ‘I did not attend that conference last year.’

✅ Năm ngoái tôi không tham dự hội nghị đó.

I did not attend that conference last year.

2. Using không for an endpoint that remains open

⚠️ Báo cáo không xong; tôi đang viết phần kết.

Mismatched for the intended ‘The report isn't finished yet’; không xong tends to describe failure or inability.

✅ Báo cáo chưa xong; tôi đang viết phần kết.

The report isn't finished yet; I'm writing the conclusion.

3. Ignoring the expectation built into chưa

⚠️ Bà ấy tám mươi tuổi nhưng chưa có con.

Grammatical, but pragmatically intrusive if no later parenthood is expected.

✅ Bà ấy không có con.

She does not have children.

4. Answering a completion question with the wrong polarity word

⚠️ — Em làm xong chưa? — Không, em sắp xong rồi.

Understandable but mismatched: không rejects the proposition without naturally expressing ‘not yet.’

✅ — Em làm xong chưa? — Chưa, em sắp xong rồi.

— Have you finished? — Not yet; I'm almost done.

5. Treating chưa as a past-tense marker

❌ Tôi chưa đi ngày mai.

Incorrect for ‘I won't go tomorrow’; chưa does not independently mark future negation.

✅ Ngày mai tôi không đi.

I'm not going tomorrow.

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Self-edit in two passes: first locate the relevant time boundary; then ask whether the speaker expects the proposition to become true after it. Only the second answer licenses chưa.

Key Takeaways

Không neutrally denies a fact, habit, intention, event, or property.
Chưa says that an expected or relevant state has not been reached by a contextually supplied boundary.
Chưa is not tied to the English present perfect; it can be evaluated in past or future contexts.
A form can be grammatical yet pragmatically wrong: không ăn and chưa ăn make different commitments.
Match short answers to the question: không for ordinary polarity, chưa for completion-by-now.

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