nechat / dát + Accusative + Infinitive

Causative constructions with nechat and dát are highly frequent across all registers of modern Czech.

1. Permissive vs. Causative Meaning

• Nechat spans both permission and causation. It implies a lack of coercion. Nechal ho odejít means "He let him leave" (permission). Here, the accusative (ho) is the agent of the infinitive, forming a true A.c.I.
• The construction dát + infinitive is often causative, implying commissioning a task or service. However, it can also express permission or yielding when paired with a dative recipient (e.g., Dej mi domluvit = Let me finish speaking). (Note: The reflexive dá se + infinitive expresses possibility, unless the reflexive se is the patient of the action, in which case it is purely causative, e.g., Dala se ostříhat = She had her hair cut). While nechat is the default for 'let/allow' with an accusative object (e.g., Nech mě jít, not *Dej mě jít), dát works well for permission with the dative.

2. Expressing or Omitting the Agent
If you want to include the person performing the commissioned task, the case depends on the verb: nechat allows the agent to be expressed either in the accusative (creating an active A.c.I., e.g., Nechal mechanika opravit auto = He had the mechanic fix the car) or in the instrumental (a passive-like construction, e.g., Nechal auto opravit mechanikem), whereas dát requires a dative agent if a bare case is used (e.g., Dal mechanikovi opravit auto). However, it is extremely common to express the agent using prepositional phrases like od + genitive or u + genitive (e.g., Dal si opravit auto u mechanika).

However, when you omit the person actually doing the work and commission a task for your own benefit, you must add the dative reflexive clitic si (benefactive si). Both nechat si and dát si are used in this exact same way, though nechat si is often more common in everyday spoken Czech. Remember that si is a second-position clitic and clusters with other pronoun objects (e.g., Nechal si ho opravit, not *Nechal opravit si ho). In this case, the accusative noun is the patient (direct object) of the infinitive, not the agent, so it is not technically an A.c.I. Compare these examples:

• Dala dokument přeložit. = She had the document translated (e.g., for work, or for someone else).
• Dala si dokument přeložit. = She had the document translated (for her own personal use).
• Nechal si opravit auto. = He had his car fixed (for himself).

3. Crucial Differences from English
English speakers frequently make two major errors with this pattern:

• Using a passive participle: English says "have it done", but Czech says "let it do" (active infinitive). Never say *Nechal auto opravené to mean "he had the car fixed" (this actually means "He left the car in a repaired state").
• Using the verb "mít": English uses "to have" for causation. In Czech, mít + infinitive expresses obligation or expectation ("I am supposed to"), not causation. Měl jsem auto opravit means "I was supposed to fix the car," not "I had the car fixed."

4. Verbal Aspect
In these causative constructions, nechat and dát function as perfective verbs for single, completed actions. For repeated or ongoing actions, you must use their imperfective counterparts nechávat and dávat (e.g., Nechával si posílat noviny = He used to have the newspaper delivered).

Note: In modern Czech, the true A.c.I. structure is primarily limited to these causative verbs, verbs of perception (like vidět or slyšet), and verbs of finding or catching (like přistihnout or najít). However, using the A.c.I. with perception verbs leans slightly literary or formal; everyday spoken Czech much more commonly uses a jak clause (e.g., Viděl jsem ho, jak přichází instead of Viděl jsem ho přicházet).