The one rule
Object becomes the subject → add the correct form of be → main verb becomes V3 (past participle) → optional by + agent. The key: the tense lives in the "be" verb, never in the main verb.
Active: Rama writes a letter. → Passive: A letter is written by Rama.
| Active tense | Passive (be + V3) |
|---|---|
| Simple Present | is / am / are + V3 |
| Present Continuous | is / am / are being + V3 |
| Present Perfect | has / have been + V3 |
| Simple Past | was / were + V3 |
| Past Continuous | was / were being + V3 |
| Past Perfect | had been + V3 |
| Simple Future | will be + V3 |
| Future Perfect | will have been + V3 |
| Modals (can/must/should) | modal + be + V3 |