Fuck it, let's talk about it
Warning: Passive voice can be used for evil! Do not do it! Do not write sentences like "The man was shot by police." No! Do not hide state violence in sentence structure!
You should use active voice when:
1. You introduce new information
2. You take or assign responsibility
Active voice is key for clarity when the sentence doesn't have anything to refer back to. If you have to put "by (person, organization)" at the end of the sentence, it should have been active voice. Ex:
Our company fucked up the project and we're sorry
NOT
Regrettably, the project was fucked up by us/on our watch/by one of our teams
But here's why passive voice is great: because it collapses who did a thing and centers the fact that it happened. When you are referring back to something the parties already agree upon, it puts the result up front.
All project review will be completed by 18 Never 2029.
NOT
Kyle | Mark | us Arch | itects, Jim's Construction, the Statesonia Department of Endangered Hummingbirds, the Federal Bureau of Staying the Fuck Out of It and like twelve other people will complete their reviews by 18 Never 2029.
No! Bad! The completion of the action matters, not the parties involved. And no, "The parties will complete their reviews" is absolutely not clearer, because it requires the same knowledge.
In fiction, passive vs active refocuses a sentence towards what you want the reader to pay attention to. Active:
A fog covered the city
Passive:
The city was covered by fog
Nothing wrong with either of them. It's just what you want the reader to think about. Bonus round: the sentence feels more natural if you put the bulk of the description in the second half, so you can add more without making it impossible to follow. Active:
A fog covered the quiet, unsuspecting city as it slept
Passive:
The city was covered by a terrible, choking fog that crept through the silent streets
These are different sentences, but nothing's wrong with either of them.
Passive voice gets a bad rap largely because even the dumbest professional development expert can ID it fairly regularly. It's bad when it makes a sentence less clear; it's good when it makes a sentence clearer. That's it.