Learn Spanish (Latin America): Para cuando cierre este ciclo, las correcciones estarán terminadas. - By the time this cycle closes, the corrections will be finished.

The phrase para cuando (by the time) is used to set a deadline. When that deadline is in the future, you must use the present subjunctive (cierre) because the action hasn't actually happened yet, making it an anticipated event rather than a stated fact.

Could we use the future tense for both verbs, like Para cuando cerrará...?

No, Spanish does not use the future tense immediately following time conjunctions like cuando or para cuando. Even though the cycle closing is a future event, the time clause requires the present subjunctive (cierre), while only the main clause takes the future tense (estarán).

Why use estarán terminadas instead of serán terminadas?

We use estar with a past participle to talk about the resulting state of an action. Estarán terminadas focuses on the state of the corrections being complete by that deadline. Using serán terminadas would form the passive voice, which focuses on the action of someone finishing them rather than the result.

Why does terminadas end in -as instead of the standard -o?