German

Verb

müssen ‎(irregular, third-person singular simple present muss, past tense musste, past participle gemusst, auxiliary haben)

1. (auxiliary, with an infinitive → “müssen” replaces the past participle) to have to (do something); must; to be obliged (to do something); to need (to do something).

   Wir müssen es machen. — “We must do it.”

   Wir müssen es nicht machen. — “We need not do it.” or “We do not need to do it.”

   Ich musste es machen. — “I had to do it.”

2. (intransitive, with past participle “gemusst”) to have to do something implied; must; to be obliged.

   Ja, ich muss. — “Yes, I must.”

   Ja, ich habe gemusst. — “Yes, I had to.”

Usage notes

• Müssen can express the necessity of doing something, but also the moral duty. Sollen expresses moral duty or the suggestion that something ought to be done. Both verbs can express a duty imposed by someone else. In this case müssen is stronger than sollen, implying that the imposing person has some kind of power to make the other really do it.
• As shown in the first line, the infinitive is used instead of the past participle in the compound tenses if the verb has a complement verb. The phenomenon is called double infinitive.

Das hätten wir machen müssen.

We should have done that.

• In southern German and Austrian speech, the infinitive is often used instead of the past participle in any construction. Thus: ich habe nicht müssen for standard ich habe nicht gemusst.
• As shown in the example above, nicht müssen translates into English as “need not” rather than “must not”. For the English “must not”, use nicht dürfen.
• Before 1996, several of the conjugated forms of müssen were spelled with an ß (that is, muß, mußte, müßte, etc.). Since the spelling reform of 1996, however, the correct spelling is with ss.

Conjugation