müssen
das Modalverb müssen
müssen is a German modal verb meaning “to have to” or “must”: muss · musst · muss.
The biggest trap: the main verb goes to the end of the sentence as an infinitive. And in the negative, nicht müssen (no need) gets mixed up with nicht dürfen (forbidden).
Conjugation: ich and er/sie/es look the same
With modal verbs, ich and er/sie/es take no ending and are identical. That holds for müssen too.
Watch du and ihr in the table: musst (double s) and müsst (umlaut + double s).
| Person | Form |
|---|---|
| ich | muss |
| du | musst |
| er / sie / es | muss |
| wir | müssen |
| ihr | müsst |
| sie / Sie | müssen |
The ich and er/sie/es forms stay muss — no ending at all.
When do you use it?
müssen expresses necessity that comes from a rule, an authority or the situation. It is your English “must” or “have to”.
| Situation | German sentence | Meaning |
|---|---|---|
| Work rule | Ich muss pünktlich sein. | I have to be on time. |
| Doctor’s orders | Du musst Wasser trinken. | You have to drink water. |
| Law / rule | Man muss an der Ampel halten. | You have to stop at a red light. |
| Your own plan | Wir müssen heute einkaufen. | We have to go shopping today. |
English “have to”, “must” and “need to” all fit into this one table.
- Ich muss jetzt gehen. I have to go now. Positive statement (necessity)
- Musst du schon weg? Do you have to leave already? Yes/no question
- Du musst nicht warten. You don’t have to wait. Negative: no need (nicht müssen)
- Er muss nicht rauchen. He doesn’t have to smoke (if he doesn’t want to, he doesn’t). Negative: 3rd person singular
- Wir müssen aufstehen. We have to get up. Separable verb (the infinitive comes together at the end)
- Das muss ich dir sagen. I have to tell you this. Object + infinitive structure
Sentence structure: modal second, infinitive last
In a statement the conjugated modal verb is in second position and the main verb (the infinitive) is at the very end.
In a question the modal verb is in first position, the subject second, and the infinitive still stays at the end.
In the negative, nicht usually stands right before the infinitive or somewhere in the middle; the infinitive still stays at the end.
| Sentence type | Structure | Example |
|---|---|---|
| Statement | Subject + modal (2nd) + … + infinitive (last) | Ich muss arbeiten. |
| Question | Modal (1st) + subject + … + infinitive (last) | Musst du arbeiten? |
| Negative | Subject + modal (2nd) + … + nicht + infinitive (last) | Ich muss nicht arbeiten. |
The main verb is never conjugated; it always stands at the end of the sentence as an infinitive.
Traps
Using “zu”
After a modal verb the infinitive comes without “zu”. It is one of the most common mistakes.
Ich muss zu arbeiten.
Never use “zu” after a modal verb.
Ich muss arbeiten.
Correct: infinitive at the end, no “zu”.
Mixing up nicht müssen and nicht dürfen
English already splits “you don’t have to” from “you mustn’t”, but a word-for-word translation of “must not” pulls you straight into the trap: in German the two live in different worlds — one is free, the other is punished.
Du musst hier nicht rauchen.
This says “You don’t have to smoke here”, not that it is forbidden.
Du darfst hier nicht rauchen.
Correct way to say it is forbidden: “You mustn’t smoke here.”
Adding -t to er/sie/es
Modal verbs have no ending in the 3rd person singular (er/sie/es); it is identical to the ich form.
Er musst arbeiten.
Regular verbs take -t (er arbeitet) but modal verbs (er muss) do not.
Er muss arbeiten.
Correct: ich muss = er muss (no ending).
What you just learned
Wir ___ heute arbeiten.
Show the answer
müssen, Müssen — müssen. With wir, sie and Sie the modal verb müssen has the same form as the infinitive; the umlaut only drops in the singular (ich muss).
“You don’t have to come.” (no need)
Show the answer
Du musst nicht kommen. — Correct. nicht müssen = no need / free choice. nicht dürfen = forbidden. Word order: subject + modal + nicht + infinitive.
The correct form for “He has to go.”:
Show the answer
Er muss gehen. — Correct. With modal verbs the er/sie/es form is the same as the ich form (muss) — no ending.
The other modal verbs
Know this before the test
The core of the topic in three lines, then the mistakes people make most often.
- müssen = to have to
Inner or outer necessity: Ich muss arbeiten · Er muss gehen. Infinitive to the end.
Ich muss heute arbeiten.
- nicht müssen = no need
The biggest modal trap: Du musst nicht kommen means “you don’t have to come”, NOT “you mustn’t come”.
Du musst nicht kommen.
- Conjugation: umlaut in the plural
ich/er muss · du musst — wir/sie müssen · ihr müsst.
musst du? · müsst ihr?
- Past: musste or the double infinitive
Präteritum is the natural choice: Ich musste früh aufstehen. If you build a Perfekt, a double infinitive appears: Ich habe arbeiten müssen.
Ich musste früh aufstehen.
Du musst nicht rauchen. (when you mean it is forbidden)
Du darfst nicht rauchen.
nicht müssen lets someone off the hook; it does not forbid.
Ich habe gestern arbeiten gemusst.
Ich habe gestern arbeiten müssen.
In the Perfekt a modal verb uses the infinitive instead of the participle (double infinitive).
Müsst du heute arbeiten?
Musst du heute arbeiten?
du → musst; müsst belongs only to ihr.
Ich muss heute arbeite.
Ich muss heute arbeiten.
After a modal, the main verb stays an INFINITIVE.
Test yourself
Tap an answer — we will look at why together.
The German for “I have to work today.”:
“You don’t have to come.” (no need)
The correct form for “He has to go.”:
The German for “Do you (all) have to come today?”:
“Smoking is not allowed here.” (no permission)
Past tense (Präteritum): “I had to get up early.”
Practice done — –
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müssen pocket card
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