In short

Chinese has two negation words, and they are not interchangeable. Use 不 (bù) for habits, states, opinions and the future (“don’t / won’t”); use 没(有) (méiyǒu) to say an action did not happen (“didn’t / haven’t”). The verb 有 (yǒu, “to have”) has only one negative form - 没有 - and never takes 不.

The rule

Both negators go in the same slot: directly before the verb or adjective. Chinese never floats the negative after the verb the way English can. What changes is which word you pick, and the choice is about meaning, not just tense.

不 (bù) - the default negator. It negates:

• habits and general facts - 我不喝咖啡。 (Wǒ bù hē kāfēi.) = I don’t drink coffee.
• present and future intentions - 我明天不去。 (Wǒ míngtiān bù qù.) = I’m not going tomorrow.
• states and qualities (adjectives) - 今天不冷。 (Jīntiān bù lěng.) = Today isn’t cold.
• the verb 是 and modal verbs - 他不是老师。 (Tā bù shì lǎoshī.) = He isn’t a teacher; 我不想去。 (Wǒ bù xiǎng qù.) = I don’t want to go.

没(有) (méiyǒu) - the “it didn’t happen” negator. It negates:

• the completion of an action - the event did not take place - 昨天她没来。 (Zuótiān tā méi lái.) = Yesterday she didn’t come.
• the verb 有 itself (possession and existence) - 我没有钱。 (Wǒ méiyǒu qián.) = I have no money.

You can write it in full (没有) or drop the 有 before another verb (没来 = 没有来); before a noun (possession) the full 没有 is the safe written form, but in speech the 有 drops there too - 屋里没人。 (Wū lǐ méi rén.) = There’s nobody in the room - and it always drops in the fixed 没什么 / 没事 / 没关系 / 没问题. 没 is always méi (2nd tone) - no sandhi.

Step 1 - is it the verb 有? If yes, the negator is 没有. Full stop. 不有 does not exist in Mandarin.

Step 2 - did an action fail to happen (in the past, or “not yet”)? Use 没(有). For “not yet” add 还 (hái): 我还没吃饭。 (Wǒ hái méi chī fàn.) = I haven’t eaten yet.

Step 3 - everything else (habit, state, opinion, 是, modal, future refusal) uses 不.

Why 有 is special. 有 already means “there is / to possess” - a state, not an action that completes - so Mandarin locked its negative to 没有 and blocks 不 entirely. Learn 有 / 没有 as a fixed pair, the way you learned 是 / 不是.

One note on 了. Because 没 already says the action did not happen, you never keep the completion particle 了 with it (say 没去, not 没去了). How 了 works is the job of Completed-action 了 (verb + 了).

Tone sandhi on 不. Its citation tone is 4th (bù). Before another 4th-tone syllable it shifts to 2nd tone (bú): 不是 bú shì, 不去 bú qù, 不贵 bú guì. Before a 1st, 2nd or 3rd tone it stays bù: 不喝 bù hē, 不来 bù lái, 不好 bù hǎo. Say each pair as one chunk.

Forms & patterns

不 vs 没(有) at a glance:

Same verb, two negators, two meanings:

不 tone sandhi:

Examples

Common mistakes

• 我不有钱。 -> 我没有钱。 (Wǒ méiyǒu qián.) - 有 is negated only by 没; 不有 does not exist in Mandarin.
• 他没是学生。 -> 他不是学生。 (Tā bù shì xuésheng.) - the verb 是 always takes 不, never 没.
• 昨天我不去。 (meaning “I didn’t go yesterday”) -> 昨天我没去。 (Zuótiān wǒ méi qù.) - a past action that did not happen needs 没, not 不.
• 我没高。 -> 我不高。 (Wǒ bù gāo.) - a state or quality (an adjective standing alone) is negated with 不, not 没.
• 我喝不咖啡。 -> 我不喝咖啡。 (Wǒ bù hē kāfēi.) - the negator goes before the verb, not after it.

Tips

• Quick test: is it an event in the past that failed to occur (or “not yet”)? Then 没. Everything else - habits, feelings, opinions, 是, “won’t” - is 不.
• 有 has exactly one negative: 没有. Memorize the pair 有 / 没有 as tightly as 是 / 不是, and you’ll never write 不有.
• English “not” is one word for every situation, so the 不 / 没 split is a genuine false-friend trap - always ask what kind of negation you mean before you pick.
• Because 没 means the action never happened, drop 了 with it: say 没去, not 没去了.