The object moves to the front, the verb becomes 'be' plus a past participle, and the subject goes to the end with 'by'.

Only three things move, and they move the same way in every tense. Everything else in this deck is that one operation applied to a different form of 'be'.

The clerk filed the report. → The report was filed by the clerk.

object first, be + participle, agent last

The clerk was filed the report by.

the three moves applied out of order

Where it bites

Choosing the wrong form of 'be'. The tense of the original verb decides it, and that is the only part of the operation that changes.