meg kell csinálni

In Hungarian syntax, the position immediately before the conjugated verb is highly regulated. When you use the modal verb kell ("must/need to") with a prefixed infinitive in a neutral sentence, the prefix leaves the infinitive and moves to the preverbal slot of kell. This rule also applies to a whole class of modal verbs, auxiliaries, and other expressions, such as fog, tud, akar, szeretne, szokott, lehet, and szabad.

Key Rules of Prefix Climbing:

• The Mechanism: The verb isn't simply being "split." Instead, the prefix (e.g., meg-, el-, ki-) climbs out of the subordinate infinitival clause into the main clause's preverbal position.
• Phonology vs. Orthography: The prefix and kell fuse into a single phonological stress unit (MEG kell csinálni). However, despite this heavy pronunciation link, the entire verbal complex must be written as three separate words (e.g., meg kell csinálni).
• Tense and Mood: Prefix climbing applies identically to the past (Meg kellett csinálni) and conditional (Meg kéne csinálni / Meg kellene csinálni) forms of kell.
• Conjugated Infinitives: The rule works exactly the same way when using Must with an Explicit Subject (e.g., Meg kell csinálnom - I must do it).
• Object Placement: In a neutral sentence, the object typically follows the entire verbal complex (e.g., Meg kell csinálni a leckét - The homework must be done).
• Focus Blocks Climbing: If another element occupies the preverbal focus slot before kell (such as an emphasized word, a question word, or the negative particle sem), the prefix is blocked from climbing and stays on the infinitive. Compare the neutral Meg kell csinálni (It must be done) with the focused MA kell megcsinálni (It must be done TODAY). If you want to focus the action itself, the entire infinitive moves to the focus position: Megcsinálni kell (It is DOING it that is necessary). If you want to emphasize the necessity itself, kell takes the primary stress and the prefix remains on the infinitive: KELL megcsinálni (It MUST be done). However, it is equally or more common in spoken Hungarian to topicalize the prefix while putting heavy stress on the modal: Meg KELL csinálni.
• Negation Blocks Climbing: Negation with Nem also takes the preverbal slot. Therefore, the negative form is Nem kell megcsinálni (It doesn't need to be done / You don't have to do it). When both focus and negation are present, the focused element comes first, followed by the negative particle, and the prefix remains on the infinitive: MA nem kell megcsinálni (It doesn't need to be done TODAY). When blocked by focus or negation, the word order becomes: [Focus/Nem] + [Conjugated Verb] + [Prefixed Infinitive]. Note for English speakers: nem kell means "don't have to" (lack of obligation). To express "must not" (negative obligation), you must use May / Allowed To in the negative: Nem szabad megcsinálni (It must not be done / You must not do it).
• Yes/No Questions: In neutral Yes/No Questions, the prefix remains climbed because there is no question word taking the focus slot (e.g., Meg kell csinálni? - Does it need to be done?).
• Intervening Words: While the standard neutral order looks like a strict 'Prefix + Modal + Infinitive' block, other words like adverbs or subjects can technically intervene between the modal and the infinitive (e.g., Meg kell gyorsan csinálni - It must be done quickly).
• Contrast with Muszáj: Unlike kell, the word muszáj (must/have to) does not typically trigger prefix climbing in standard Hungarian (Muszáj megcsinálni). However, in colloquial speech, native speakers frequently apply prefix climbing to muszáj by analogy (e.g., Meg muszáj csinálni).

This pattern is ubiquitous across all registers of Hungarian. Using the non-climbed order (kell megcsinálni) without a specific focus element is ungrammatical.