Must and Have ToA2

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Must and have to for obligation; mustn't for prohibition; don't have to for no obligation. Mustn't forbids and don't have to means it is not necessary: You mustn't park here. You don't have to pay.

No information at the current level. This view starts at A2: choose A2 or a higher level.

CheatsheetA2

Point	Rule	Example
Form: must	subject + must + V; one form for every subject	She must study.
Form: have to	have to, but has to with he, she, it	We have to leave. / He has to leave.
Question, negative	have to takes do / does / did and then the base form	Do you have to leave? / She doesn't have to leave.
must	the speaker's own view or a written rule	I must save more money. / Visitors must sign in.
have to	the situation or another person decides; common in speech	I have to get up at six for work.
mustn't	forbidden	You mustn't use your phone here.
don't have to	not necessary: you can choose	You don't have to come.
Trap	had to is the past of must	I had to work on Saturday.

Form: mustA2

Form	Pattern	Example
Affirmative	subject + must + V	She must study.
Negative	subject + mustn't + V	You mustn't touch it.
Question	Must + subject + V	Must I go now?

must has one form for every subject and takes the base verb: She must study.
must has no past form. The past is had to.
Questions with must are formal and rare. Speech prefers Do I have to…?

Form: have toA2

Form	Pattern	Example
Affirmative (I / you / we / they)	have to + V	We have to leave.
Affirmative (he / she / it)	has to + V	He has to leave.
Negative	don't / doesn't have to + V	She doesn't have to leave.
Question	Do / Does + subject + have to + V	Do you have to leave?
Past	had to + V	I had to leave.
Past negative and question	didn't have to / Did … have to	Did you have to pay?

have to works like a main verb: it takes do / does / did in questions and negatives.
After do / does / did the verb is in the base form: Does she have to leave?

Pronunciation: have to and mustA2

Form	Sound	Example
have to	/ˈhæf tə/	I have to go. /aɪ ˈhæf tə ɡəʊ/
has to	/ˈhæs tə/	She has to go. /ʃi ˈhæs tə ɡəʊ/
had to	/ˈhæd tə/	We had to go. /wi ˈhæd tə ɡəʊ/
mustn't	/ˈmʌsnt/	You mustn't go. /juː ˈmʌsnt ɡəʊ/

Before to the final sound of have changes to /f/, has to /s/ and had stays /d/.
The first t of mustn't is silent.

UseA2

Use	Example
Personal obligation: the speaker decides (must)	I must save more money.
Written rules and signs (must)	Visitors must sign in.
Strong recommendation (must)	You must try this cake!
Obligation from the situation or another person (have to)	I have to get up at six for work.
Prohibition (mustn't)	You mustn't use your phone here.
No obligation: it is not necessary (don't have to)	You don't have to come.
Past obligation (had to)	I had to work on Saturday.

must expresses the speaker's own view or a written rule; have to expresses facts outside the speaker.
In everyday speech have to is more common than must.
For advice that is not an obligation see Should.

Compare: mustn't and don't have toA2

Point	mustn't	don't have to
Meaning	forbidden	not necessary: you can choose
Example	You mustn't tell Ana. It's a secret.	You don't have to tell Ana. I can do it.
Example	Children mustn't cross alone.	Children don't have to wear a uniform.

Typical errorsA2

✗	✓	Rule
You don't must smoke here.	You mustn't smoke here.	negative of must = mustn't
She musts go.	She must go.	must has no -s
She must to go.	She must go.	must + base verb; no to
He have to work.	He has to work.	he / she / it → has to
Do I must go?	Do I have to go? / Must I go?	have to takes do; must forms its own question
She doesn't has to work.	She doesn't have to work.	doesn't + base form
I must work yesterday.	I had to work yesterday.	past of must → had to