An infinitive clause — a zu-clause — is a subordinate clause stripped of its own subject. Instead of spelling out who does the action, it leans on the main clause for that information: Es ist wichtig, pünktlich zu sein ("It's important to be on time"), Ich habe vergessen, dich anzurufen ("I forgot to call you"). The construction is compact and extremely common, but it carries one hard restriction that governs everything else: a zu-clause has no subject of its own, so it can only be used when the doer is already supplied by the main clause. This single fact explains why German cannot translate "I want you to come" with an infinitive at all.
What a zu-clause is
A zu-clause consists of, at minimum, the particle zu plus an infinitive, sitting at the very end of the clause. Everything else — objects, adverbs, prepositional phrases — piles up in front of zu.
Es ist wichtig, pünktlich zu sein.
It's important to be on time. (zu sein closes the clause; pünktlich precedes it)
Ich versuche, jeden Tag eine Stunde zu lesen.
I try to read for an hour every day. (informal — zu lesen at the very end)
Sie hofft, bald einen neuen Job zu finden.
She hopes to find a new job soon. (zu finden last, with the object einen neuen Job stacked before it)
The infinitive and its zu are the anchor at the end; read the clause and you will find them in the final slot every time. This mirrors the verb-final habit of all German subordinate clauses — the difference is that a zu-clause has an infinitive there instead of a conjugated verb, because it has no subject to conjugate for.
The shared-subject rule — the insight that explains everything
Here is the rule competitors gloss over. A zu-infinitive clause has no subject, so its implied doer must be the same as the main clause's subject (or, with some verbs, the main clause's object). The infinitive's subject is "understood" from the main clause; if there is nobody in the main clause to supply it, you cannot use a zu-clause.
Ich hoffe, bald zu kommen.
I hope to come soon. (the one who hopes and the one who comes are both 'I' — shared subject)
Because the subject is shared, Ich hoffe, bald zu kommen can only mean I will come — never someone else. This is exactly why the English pattern "I want you to come" has no infinitive equivalent in German. The wanting is done by ich, but the coming would be done by du — two different subjects. German has no "want someone to" infinitive construction (linguists call the English version ECM, exceptional case marking). When the subjects differ, you must switch to a dass-clause:
Ich will, dass du kommst.
I want you to come. (different subjects → a dass-clause is required, not an infinitive)
Ich hoffe, dass du bald kommst.
I hope you come soon. (different subjects: hoping is mine, coming is yours)
Compare the pair directly: Ich hoffe, bald zu kommen (I come) versus Ich hoffe, dass du bald kommst (you come). The zu-clause is available only when the doer is the same person already named in the main clause. The moment a new doer appears, German reaches for dass.
zu nests inside separable verbs
When the infinitive is a separable verb, zu does not sit in front of the whole word — it slots between the prefix and the stem, and the three pieces are written as one word: anrufen → anzurufen, aufstehen → aufzustehen, mitkommen → mitzukommen.
Ich habe vergessen, dich anzurufen.
I forgot to call you. (anrufen → anzurufen, written as one word)
Es fällt mir schwer, früh aufzustehen.
I find it hard to get up early. (aufstehen → aufzustehen)
This is purely mechanical but easy to forget: with an inseparable verb you write two words (zu verstehen), but with a separable verb the zu is swallowed into the middle and the result is a single word (anzurufen). Getting zu anrufen wrong is one of the most common B1 slips.
What triggers a zu-clause
zu-clauses appear as the complement of a wide range of triggers. It helps to see that they fall into families.
| Trigger type | Examples | Model |
|---|---|---|
| Verbs of trying/planning/forgetting | versuchen, planen, vergessen, beginnen, aufhören, vorhaben | Ich versuche, ruhig zu bleiben. |
| Verbs of hoping/wishing/intending | hoffen, beabsichtigen, sich entscheiden, sich freuen | Sie hofft, zu gewinnen. |
| Adjective + sein | wichtig, schön, schwer, möglich, leicht | Es ist schön, dich zu sehen. |
| Noun + haben | Lust, Zeit, Angst, die Möglichkeit, keine Idee | Ich habe keine Lust, zu kochen. |
Hast du Lust, heute Abend essen zu gehen?
Do you feel like going out to eat tonight? (informal — noun Lust triggers the zu-clause)
Es ist nicht leicht, eine Fremdsprache zu lernen.
It isn't easy to learn a foreign language. (adjective leicht as trigger)
A small group of common verbs — the modals plus sehen, hören, lassen, gehen, bleiben — take a bare infinitive without zu (Ich kann schwimmen, Ich gehe schwimmen). Those are treated on the bare-infinitive page; do not insert zu after them.
Commas with zu-clauses
Under the current (post-2006) German rules, the comma before a zu-clause is optional for a bare zu-infinitive but is normally written for clarity, and it is obligatory when the clause is extended (has its own objects or modifiers) or when it is introduced by um, ohne, anstatt, statt, als.
Ich versuche zu schlafen.
I'm trying to sleep. (bare infinitive — comma optional)
Ich versuche, vor Mitternacht zu schlafen.
I'm trying to sleep before midnight. (extended clause — comma required)
Sie ging, ohne sich zu verabschieden.
She left without saying goodbye. (ohne…zu always takes a comma)
Most writers simply set the comma in every case, which is always allowed and never wrong. The constructions um…zu ("in order to"), ohne…zu ("without …-ing"), and anstatt…zu ("instead of …-ing") are infinitive clauses too, with their own page; they always require the comma and they likewise demand a shared subject.
English contrast
English infinitive clauses are far more permissive. English freely says "I want you to come," "I expect them to win," "I'd like him to stay" — the infinitive happily takes a subject of its own (in the accusative: you, them, him). German shuts this door: its infinitive clause is subjectless and must borrow its doer from the main clause. Where English changes doer with an infinitive, German switches to a finite dass-clause. The other contrast is purely orthographic: English keeps "to" as a separate word always (to call up), while German buries zu inside a separable verb (anzurufen).
Common Mistakes
❌ Ich will, dich zu sehen.
Incorrect — wanting is mine but the seeing involves you; mismatched subjects can't use a zu-clause. (Here the intended meaning needs care.)
✅ Ich will dich sehen.
I want to see you. (one subject: I do both the wanting and the seeing; wollen takes a bare infinitive)
❌ Ich hoffe, du zu kommen.
Incorrect — a zu-clause cannot contain its own subject (du); a different subject requires dass.
✅ Ich hoffe, dass du kommst.
I hope you come.
❌ Ich habe vergessen, dich zu anrufen.
Incorrect — with a separable verb, zu goes inside: anzurufen, written as one word.
✅ Ich habe vergessen, dich anzurufen.
I forgot to call you.
❌ Es ist wichtig pünktlich zu sein.
Incorrect — an extended zu-clause needs a comma before it.
✅ Es ist wichtig, pünktlich zu sein.
It's important to be on time.
❌ Ich kann zu schwimmen.
Incorrect — modal verbs take a bare infinitive, no zu.
✅ Ich kann schwimmen.
I can swim.
Key Takeaways
- A zu-clause is a subjectless subordinate clause ending in zu + infinitive.
- Its doer is borrowed from the main clause — the subjects must match (or the trigger verb's object supplies it).
- When the doer differs, German has no infinitive option: use a dass-clause (Ich will, dass du kommst).
- With separable verbs, zu nests inside and the word is written together: anzurufen, aufzustehen.
- The comma is obligatory for extended clauses and for um/ohne/anstatt…zu; always writing it is safe.
- Modals and a few others (gehen, sehen, hören, lassen) take a bare infinitive without zu.
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Start learning German→Related Topics
- The zu-InfinitiveB1 — When German uses zu + infinitive at the end of a clause, when it doesn't (modals and perception verbs take a bare infinitive), and where zu goes inside separable verbs.
- um...zu, ohne...zu, (an)statt...zuB1 — The three infinitive conjunctions for purpose, 'without doing', and 'instead of doing' — and the same-subject rule that forces damit when subjects differ.
- dass-Clauses and Complement ClausesB1 — A dass-clause is a subordinate clause that serves as the object of a verb of saying, thinking, or feeling — verb-final, comma before dass — alongside the ob-clause for indirect yes/no questions and the dass-less V2 variant of casual speech.
- zu vs um...zu vs damit (purpose and complement)B2 — Three constructions learners confuse: plain zu for verb complements, um...zu for same-subject purpose, and damit for different-subject purpose.
- Separable Verbs with zu, Modals, and in Subordinate ClausesB1 — The three contexts where separable verbs do not split: with zu (nesting it inside), after a modal, and in verb-final subordinate clauses.