Infinitive Constructions & Causatives

German uses several distinct constructions whenever a sentence needs more than one verb idea, or needs to express "in order to," "don't need to," or "to have something done." This guide collects all of them in one place: Infinitiv mit zu, its three blocking exceptions, the um...zu vs. damit purpose clauses, brauchen + zu as an alternative to müssen, and the lassen + Infinitiv causative.

Infinitiv mit zu — Core Rule

Infinitiv mit zu (also called zu plus Infinitiv / zu mit Infinitiv) is used whenever a German sentence needs two main verbs describing two linked actions/ideas. The infinitive is the dictionary/unconjugated form of the verb.

Identifying trigger: if the English sentence contains the word "to" linking two actions (and it isn't a modal-verb sentence), that's the cue that German needs zu + infinitive.

Structure:

• The first main verb is conjugated normally, in its usual position.
• Put a comma, then the rest of the sentence.
• The second main verb goes to the end of the clause, in its infinitive form, together with zu.
• zu here is not the dative preposition zu — it is just a fixed grammatical marker glued to the second verb.
• With separable (trennbar) verbs, zu is inserted in the middle, between the prefix and the verb stem: an + zu + rufen → anzurufen; mit + zu + bringen → mitzubringen.

Examples

• Ich plane, nach Deutschland zu gehen. → I am planning to go to Germany. (planen + gehen)
• Ich helfe meiner Schwester, Deutsch zu lernen. → I am helping my sister to learn German. (helfen + lernen; helfen is a dative verb, so "my sister" → meiner Schwester)
• Ich hoffe, die Prüfung zu bestehen. → I am hoping to pass the exam.
• Ich denke daran, meinen Bruder anzurufen. → I am thinking of calling my brother. (separable verb anrufen → anzurufen; takes Akkusativ, so meinen Bruder)
• Er versucht, dieses Problem zu lösen. → He is trying to solve this problem.
• Wir haben uns entschieden, in den Urlaub zu gehen. → We have decided to go on vacation. (reflexive uns is retained)
• Sie hat vergessen, mich anzurufen. → She has forgotten to call me.
• Ich habe vorgehabt, eine Woche nach Berlin zu fahren. → I had planned to go to Berlin for a week.

Identifying the "two main verbs": haben/sein as main verbs vs. helping verbs

Before applying the rule, check whether the sentence really has two main verbs — haben and sein are not always helpers; they are full main verbs in their own right:

• Ich habe Angst. → I am afraid. (haben = main verb)
• Ich habe einen Kuli. → I have a pen. (haben = main verb)
• Ich bin Student. → I am a student. (sein = main verb). Note: never use an article before a profession — Ich bin Student, not Ich bin ein Student.

Contrast with haben/sein as helping verbs in the Perfekt (with Partizip II): Ich habe das Haus gemacht. (haben = helper, main verb = machen); Ich bin um acht Uhr aufgestanden. (sein = helper, because aufstehen is a movement/change-of-state verb).

Once haben/sein are recognized as possible main verbs, more sentence shapes can trigger zu + infinitive:

• haben + noun + zu-infinitive:
  • Ich habe Lust, eine Pizza zu essen. → I have a desire to eat a pizza.
  • Ich habe den Wunsch, nach Deutschland zu gehen. → I have the wish to go to Germany.
  • Ich habe Zeit, ins Restaurant zu gehen. → I have time to go to the restaurant.
  • Ich habe Angst, dich anzurufen. → I have fear of calling you.
• sein + adjective + zu-infinitive:
  • Es ist wichtig, jeden Tag Deutsch zu lernen. → It is important to learn German every day.
  • Es ist so schön, am Strand zu liegen. → It's so nice to lie on the beach.

The Three Exceptions: When NOT to Use zu + Infinitive

Even when the English sentence has the word "to," German does not use zu + infinitive in three situations:

1. Modal verbs

If a modal verb (möchten, müssen, wollen, sollen, können, dürfen) is present, use the modal verb word order instead: modal verb in second position, main verb at the end in plain infinitive (no zu).

• Ich möchte eine Pizza essen. → I would like to eat a pizza. (NOT Ich möchte, eine Pizza zu essen)

Even though "to eat" appears in the English sentence, the modal verb rule overrides zu + infinitive entirely.

2. Double-infinitive verbs (verb + verb combos like "schlafen gehen")

Some verb pairs (e.g. einkaufen gehen, schlafen gehen, schwimmen gehen) function as a single combined verb, not two separate main verbs. They behave like a separable verb: the "go" part takes second position, the other infinitive goes to the end — and no zu appears anywhere.

• Ich gehe einkaufen. → I am going shopping. (NOT Ich gehe, einzukaufen)
• Ich gehe schlafen. → I am going to sleep.
• Ich gehe im See schwimmen. → I am going swimming in the lake. (NOT Ich gehe in die See zu schwimmen — wrong both for the unwanted zu and for the wrong movement-style case)

Rule of thumb: if the two verbs together form one fixed idiomatic action (go + [verb]), treat it as one double-infinitive verb, not two main verbs — the "two main verbs" condition for zu + infinitive simply doesn't apply.

3. Future tense with werden

werden used as a future auxiliary is a helping verb, not a main verb, so it never triggers zu + infinitive on its own.

• Ich werde jeden Tag Deutsch lernen. → I will learn German every day. (NOT Ich werde, jeden Tag Deutsch zu lernen)
• Ich werde spazieren gehen. → I will go for a walk. (gehen here is the double-infinitive verb; werden stays a pure helper)

But — if a sentence has werden (future helper) plus a genuine second main verb (three verb-ideas: will + try + learn), the zu + infinitive rule comes back into play for that second pair, because werden itself doesn't count toward "two main verbs":

• Ich werde versuchen, jeden Tag Deutsch zu lernen. → I will try to learn German every day. (werden = future helper; versuchen + lernen = the two main verbs that trigger zu lernen)
• Ich werde anfangen, täglich Deutsch zu lernen. → I will start to learn German daily.

um...zu vs. damit (Purpose Clauses)

Both constructions translate roughly as "in order to" / "so that," but they are not always interchangeable — the deciding factor is whether the subject of both clauses is the same.

um...zu — same subject only

um...zu = "in order to." Strict requirement: the subject of both clauses must be the same. Because of this, um...zu never includes its own subject — the second clause is simply the same person doing the second action, so no subject needs to be stated.

• Ich lerne Deutsch, um nach Deutschland zu gehen. → I am learning German in order to go to Germany. (I learn, I go — same subject)
• Ich trinke Wasser, um fit zu bleiben. → I am drinking water in order to stay fit.

Word order: comma, then um at the start of the clause, with the main verb pushed to the end in infinitive form, preceded by zu (...um ... zu + Infinitiv).

damit — subjects can differ

damit = "so that." No subject restriction — the subject of the second clause can be the same or different from the first clause's subject, which gives damit a much wider range of use.

• Ich erkläre langsam, damit er mich versteht. → I am explaining slowly so that he understands me. (subject 1 = I; subject 2 = he — different, so only damit works here)
• Ram arbeitet hart, damit seine Mutter sich freut. → Ram works hard so that his mother is happy. (different subjects)

Word order: comma, then damit, with the subject in second position right after damit, and the conjugated verb pushed to the end of the clause — not an infinitive, since the damit clause has its own subject.

When subjects are the same: either works (with one scoring nuance)

When both clauses share a subject, you can usually choose either construction:

• Sie arbeitet hart, um ihre Ziele zu erreichen. = Sie arbeitet hart, damit sie ihre Ziele erreicht. → both mean "She is working hard (in order) to reach her goals."
• Felix ruft seine Freunde an, um sie zum Abendessen einzuladen. → Felix calls his friends in order to invite them to dinner. Since the subject is the same in both clauses (Felix), um...zu is the preferred/expected construction in exam answers — a grammatically correct damit-version (Felix ruft seine Freunde an, damit er sie zum Abendessen einladen kann.) may be marked down if the question specifically targets um...zu. Rule of thumb: when both clauses can correctly use um...zu (same subject), prefer it; only switch to damit when subjects differ or the question calls for it.

Modal verbs inside um...zu / damit clauses

A B2.1-level refinement: when building an um...zu or damit clause, drop any modal verb that would otherwise appear in the second clause and keep only the main verb — with one exception: können, which is always retained.

• Ich lerne Deutsch, weil ich nach Deutschland fliegen will. (has modal will) → rebuilt by dropping will and keeping only fliegen: Ich lerne Deutsch, damit ich nach Deutschland fliege. → I am learning German so that I can/will fly to Germany.
• Der Lehrer spricht langsam, damit die Kinder ihn verstehen können. → The teacher speaks slowly so that the children can understand him. (können stays, fully conjugated, after the main verb)
• Er macht eine Ausbildung, um viel Geld verdienen zu können. → He is doing an apprenticeship (in order) to be able to earn a lot of money. (main verb verdienen goes to the end as infinitive, followed by infinitive können, with zu attached just before it: ...verdienen zu können.)
• Contrast with damit: Er macht eine Ausbildung, damit er Geld verdienen kann. → here kann is fully conjugated (3rd person singular), because damit clauses always carry a conjugated verb at the end, not an infinitive.

brauchen + zu (Müssen-Alternative)

brauchen + zu is a stylistic/grammatical alternative to the modal verb müssen, used especially in negative sentences ("don't need to / don't have to").

Structure: subject + brauchen (conjugated, position 2) + [nicht/kein/nur] + ...

• zu + Infinitiv (at the end). Unlike the general Infinitiv-mit-zu structure, no comma is used before the zu-infinitive when brauchen governs it — it counts as one fused grammar pattern, not two separate clauses.

• Ich brauche heute nicht zu lernen. = Ich muss heute nicht lernen. → I don't need to learn today.
• Er braucht kein Handy zu kaufen. = Er muss kein Handy kaufen. → He doesn't need to buy a phone.
• Du brauchst keine Kamera mitzubringen. → You don't need to bring a camera. (separable verb mitbringen → mitzubringen, zu inserted between prefix and stem, exactly as in the general Infinitiv-mit-zu rule)
• Du brauchst mir nicht zu helfen. = Du musst mir nicht helfen. → You don't need to help me.
• Ich brauche keine Tabletten mehr zu nehmen. = Ich muss keine Tabletten mehr nehmen. → I no longer need to take any tablets.
• Er braucht die Pflegerin nur zu fragen. = Er muss die Pflegerin nur fragen. → He just needs to ask the nurse.

Negation options: nicht, kein, or nur can all be used with brauchen + zu, with slightly different shades of meaning — but all function as a direct, interchangeable alternative to müssen (+ nicht) + Infinitiv, useful for varying sentence structure on the exam.

lassen + Infinitiv (Causative)

lassen + Infinitiv expresses "to let/have something done [by someone else]" — the causative construction, used when the subject arranges for an action rather than performing it personally.

• Lässt du dich lieber beraten, oder bestellst du im Internet? → Do you prefer to let yourself be advised, or do you order online?
• Ich bestelle lieber online und lasse mir die Ware liefern. → I prefer to order online and have the goods delivered to me.
• Meine Eltern lassen lieber die alten Sachen reparieren. → My parents prefer to have the old things repaired.
• Ich lasse mir die Haare schneiden. → I am having/letting my hair be cut [by someone else] (since you can't cut your own hair, this uses lassen; the body-part object still takes the definite article, not a possessive).

The perfect-tense quirk: both verbs stay infinitive, with haben

Normally, the Perfekt is built as haben/sein (2nd position) + Partizip II at the end. With lassen, a special B1 rule applies instead: even in the perfect tense, the construction keeps both the main verb and lassen in the infinitive — neither becomes a participle — and both sit at the end of the clause, after the helping verb.

• Ich habe es reparieren lassen. → I had it repaired. (NOT Ich habe es reparieren gelassen in this usage)
• Mein Handy ist mir runtergefallen. Ich habe es im Handyladen reparieren lassen. → My phone fell. I had it repaired at the phone shop.
• Meine Eltern haben vor dem Urlaub ihr Fahrrad reparieren lassen. → My parents had their bicycle repaired before the vacation.
• Meine Schwester hat ihr Kleid nähen lassen. → My sister had her dress sewn.
• Ich habe auf dem Laptop ein Fremdprogramm installieren lassen. → I had a third-party program installed on my laptop.

The helping verb is always haben with this construction — even when the main verb would normally take sein as a movement/change-of-state verb (e.g. fallen). This is because the focus of the sentence is "you got it done by somebody else," not the movement itself — so haben overrides the usual sein-selection rule whenever lassen is the governing causative verb.

Source Videos

• video-02-notes.md — Infinitiv mit zu core rule, identifying "two main verbs," haben/sein as main vs. helping verbs, and the three exceptions (modal verbs, double-infinitive verbs, future with werden).
• video-04-notes.md — Infinitiv mit zu recap embedded in the Anna & Paula vacation-planning chat (additional worked examples).
• video-08-notes.md — lassen + Infinitiv causative construction, including the perfect-tense quirk (both verbs stay infinitive, haben as helper regardless of the main verb's normal auxiliary).
• video-09-notes.md — homework recap drilling lassen + Infinitiv in the perfect tense with further worked examples.
• video-20-notes.md — um...zu vs. damit: the same-subject restriction, word order for both, and the können exception when dropping modal verbs from purpose clauses.
• video-33-notes.md — brauchen + zu as a müssen-alternative (structure, negation options, no comma before zu).
• video-35-notes.md — brauchen + nicht + zu drilled against nicht müssen, and the um...zu vs. damit same-subject preference rule confirmed via test-review correction.