Future Anteriority

Hungarian uses several primary strategies to build the meaning of a future perfect action. Note that without contextual deadline markers like holnapra (by tomorrow) or addigra (by then), the first two strategies default to the simple perfective future (e.g., "I will do it"). The "future perfect" meaning ("I will have done it") relies entirely on these contextual clues.

• Perfective Present: This is the most common method. Attach a perfective verbal prefix (like meg-, el-, be-) to a present-tense verb. The prefix provides the "completed" aspect, while the context (e.g., "by tomorrow") provides the future timeframe. In negative sentences, the prefix detaches and moves behind the verb (e.g., holnapra nem csinálom meg - by tomorrow I will not have done it).
• Future with fog + Perfective Infinitive: You can also use the future with fog combined with a perfective infinitive. This strategy is largely interchangeable with the Perfective Present for expressing future perfect meanings. Crucially, when using a perfective prefix with fog in neutral affirmative sentences, the prefix detaches from the infinitive and jumps in front of fog (e.g., addigra meg fogom csinálni - by then I will have done it). However, if there is a focused element (such as nem, a question word, or an emphasized subject), it takes the focus position before fog, and the prefix stays attached to the infinitive (e.g., addigra nem fogom megcsinálni - by then I will not have done it, addigra ki fogja megcsinálni? - by then who will have done it?).
• Past Tense + majd (ha), amikor, or miután: Use the past tense paired with majd (later), majd ha (when [in the future]), amikor (when), or miután (after). The past tense here is relative—it shows the action is "past" (completed) relative to the future moment, not the present. In neutral sentences using this strategy, the prefix stays attached to the past tense verb (e.g., Majd ha megcsináltam... - When I have done it...).
• Periphrastic Stative: Combine the future auxiliary lesz with an adverbial participle. This emphasizes the resulting state (e.g., "will be in a state of having been done"). For transitive verbs, this construction is passive in nature; the subject of the sentence must be the receiver of the action, not the doer (e.g., Addigra a munka meg lesz csinálva - By then the work will have been done). Intransitive verbs can also use this to describe a state (e.g., addigra el lesz tévedve - by then will be lost). Note that prefix behavior with lesz mirrors that of fog: the prefix jumps in front of lesz in neutral sentences (addigra meg lesz csinálva - by then will have been done) but stays attached to the participle in negative or focused sentences (addigra nem lesz megcsinálva - by then will not have been done).

Important Triggers and Distinctions: Future perfect scenarios are frequently triggered by conjunctions like mire (by the time) and addigra (by then). Furthermore, never combine fog or lesz with a past-tense conjugated verb—this is a common error and grammatically impossible in Hungarian.