What Is Passive Voice with Modals?
In English, we use modal verbs — such as can, could, may, might, must, should, will, have to, and ought to — to express ability, possibility, permission, obligation, and advice. When we combine these modals with the passive voice, we shift the focus from the person performing the action to the action itself or the object receiving the action. This is what we call passive voice with modals.
In active sentences, the subject does the action: "They must clean the office." In passive sentences with modals, the object becomes the subject, and the doer is either moved to the end with "by" or left out entirely: "The office must be cleaned." We use this structure when the action matters more than who performs it, when the doer is unknown, or when we want to sound more formal and impersonal.
The passive voice with modals is extremely common in formal writing, rules, regulations, news reports, academic texts, and everyday instructions. Mastering this structure will help you express ideas with greater flexibility and precision in English.
The core pattern for passive voice with modals is always the same: modal + be + past participle (V3). No matter which modal you use, this formula does not change.
When Do We Use It?
We use the passive voice with modals in several important situations. Understanding when to use this structure is just as important as knowing how to form it. Here are the main reasons we choose passive voice with modals:
| Purpose | Explanation | Example |
|---|---|---|
| Unknown doer | We do not know who does the action | The window might be broken by someone tonight. |
| Unimportant doer | Who does it does not matter | The report must be submitted by Friday. |
| Rules & regulations | Official instructions, signs, laws | Mobile phones must be switched off during the exam. |
| Formal tone | Academic, professional, or official writing | Further research should be conducted on this topic. |
| Focus on the action | The action or result is more important | The building can be seen from the highway. |
| Giving advice | Suggesting what needs to happen | The walls should be painted before the furniture arrives. |
| Expressing possibility | Something is possible or likely | The flight may be delayed due to fog. |
You do not always need to include "by + agent" in passive sentences. If the doer is obvious, unknown, or unimportant, simply leave it out. For example: "The homework should be finished before class" — we do not need to say "by the students" because it is already understood.
Affirmative Passive with Modals
To form the affirmative passive with modals, we follow one simple formula. The subject receives the action, the modal stays in its base form, and we add be followed by the past participle (V3) of the main verb.
Subject + modal + be + past participle (V3)
The modal verb never changes form — it does not take -s, -ed, or -ing. The word "be" always stays as "be" (never "is", "am", or "are") when it follows a modal.
| Modal | Active Voice | Passive Voice |
|---|---|---|
| can | They can fix the car. | The car can be fixed. |
| could | She could solve the problem. | The problem could be solved. |
| may | They may cancel the event. | The event may be cancelled. |
| might | Someone might steal the painting. | The painting might be stolen. |
| must | You must wear a helmet. | A helmet must be worn. |
| should | We should inform the parents. | The parents should be informed. |
| will | They will deliver the package. | The package will be delivered. |
| have to | You have to complete the form. | The form has to be completed. |
| ought to | We ought to respect the rules. | The rules ought to be respected. |
Do not conjugate "be" after a modal. It must always remain as be:
✘ The letter must is sent today.
✔ The letter must be sent today.
✘ The windows can are cleaned.
✔ The windows can be cleaned.
Negative Passive with Modals
To make the passive voice with modals negative, we simply add not after the modal verb. The rest of the structure stays the same. In everyday speech and informal writing, contractions are common.
Subject + modal + not + be + past participle (V3)
Common contractions: can't, couldn't, won't, shouldn't, mustn't, might not, may not. Note that "may not" and "might not" are rarely contracted in formal writing.
| Modal | Negative Passive Example |
|---|---|
| cannot / can't | This document cannot be copied without permission. |
| could not / couldn't | The damage couldn't be repaired in time. |
| may not | The results may not be published until next week. |
| might not | The concert might not be held outdoors. |
| must not / mustn't | This area must not be entered without authorisation. |
| should not / shouldn't | Children shouldn't be left alone near the pool. |
| will not / won't | Late applications will not be accepted. |
| do not have to | The uniform does not have to be worn on Fridays. |
| ought not to | Such decisions ought not to be made in haste. |
Do not place "not" after "be" — it must come directly after the modal:
✘ The package should be not opened.
✔ The package should not be opened.
Must not be done = it is forbidden (prohibition).
Does not have to be done = it is not necessary (no obligation).
"Phones must not be used during the test." → It is against the rules.
"Phones don't have to be switched off in the library." → It is your choice; there is no rule.
Question Form with Modal Passives
To form questions with the passive voice and modals, we move the modal verb to the beginning of the sentence (before the subject). The rest of the structure remains the same. For information questions, we add a question word (what, where, when, how, etc.) before the modal.
Modal + subject + be + past participle (V3) ?
Wh- word + modal + subject + be + past participle (V3) ?
| Type | Question |
|---|---|
| Can | Can this problem be solved? |
| Could | Could the meeting be rescheduled? |
| Should | Should the windows be opened? |
| Must | Must this form be filled in by hand? |
| Will | Will the project be completed on time? |
| Wh- + can | Where can tickets be purchased? |
| Wh- + should | How should this medicine be taken? |
| Wh- + must | When must the assignment be handed in? |
| Wh- + will | Where will the ceremony be held? |
| Wh- + could | How could this mistake be avoided? |
Since "have to" is not a true modal, it uses do/does to form questions:
"Does the essay have to be typed?"
"Do the rooms have to be booked in advance?"
Special Cases and Rules
While the basic formula for passive voice with modals is straightforward, there are several special cases and important rules to keep in mind. These details will help you use the structure accurately and naturally.
| Special Case | Rule | Example |
|---|---|---|
| By + agent | Include the agent only when it adds important information | The novel should be read by every student. |
| Two objects | Verbs with two objects (give, send, offer) can make either object the subject | She can be given a second chance. |
| Phrasal verbs | Keep the preposition/particle attached to the verb | The meeting can't be put off any longer. |
| Have to | "Have to" changes to "has to" with he/she/it | The report has to be reviewed by the manager. |
| Ought to | "Ought to" keeps "to" before "be" in the passive | The rules ought to be followed at all times. |
| Intransitive verbs | Verbs without objects (happen, arrive, sleep) cannot be made passive | ✘ It can be happened. |
Not all verbs can be made passive. Intransitive verbs (verbs that do not take an object) cannot have a passive form:
✘ The accident must be happened yesterday.
✔ The accident must have happened yesterday.
✘ The baby should be slept more.
✔ The baby should sleep more.
When a phrasal verb is used in the passive, do not separate the verb from its particle. The preposition or particle stays right after the past participle:
"The rubbish must be thrown away." (not "thrown the rubbish away")
"The lights should be turned off before leaving."
Unlike true modals, "have to" changes form depending on the subject and tense:
✔ The form has to be signed. (he/she/it)
✔ The forms have to be signed. (I/you/we/they)
✔ The form had to be signed yesterday. (past)
True modals (can, must, should, will, etc.) never change form.
The passive voice is not about hiding the doer — it is about shining a light on what truly matters: the action and its result.
— The Grammar GazetteExample Sentences
Below you will find a variety of example sentences organised by type. Study these carefully to see how passive voice with modals is used in different contexts and with different modal verbs.
Active to Passive Conversion with Modals
Converting an active sentence to a passive sentence with modals follows a clear, step-by-step process. Once you learn these steps, you can transform any active modal sentence into its passive equivalent.
Step 1: Find the object of the active sentence → make it the new subject.
Step 2: Keep the modal verb the same.
Step 3: Add be after the modal.
Step 4: Change the main verb to its past participle (V3) form.
Step 5: Add "by + agent" only if the doer is important.
| Active | → | Passive |
|---|---|---|
| You must finish the project. | → | The project must be finished. |
| They can speak English here. | → | English can be spoken here. |
| She should invite all the guests. | → | All the guests should be invited. |
| We will announce the winner tomorrow. | → | The winner will be announced tomorrow. |
| Someone might steal the bicycle. | → | The bicycle might be stolen. |
| The doctor could treat the patient. | → | The patient could be treated by the doctor. |
| You may use the computer. | → | The computer may be used. |
| We have to check the answers. | → | The answers have to be checked. |
| They ought to protect the environment. | → | The environment ought to be protected. |
Do not forget the word be between the modal and the past participle:
✘ The homework must finished today.
✔ The homework must be finished today.
✘ The letter can sent by post.
✔ The letter can be sent by post.
Include "by + agent" when the doer adds new or important information:
"The painting must be restored by a professional." (important — not just anyone)
"The floors should be cleaned." (no need to say "by someone" — it is obvious)
Short Answers with Modal Passives
When answering yes/no questions in the passive voice with modals, we use short answers. Short answers use only the subject and the modal (positive or negative). We do not repeat "be + past participle" in the short answer.
| Question | Short Answer (Yes) | Short Answer (No) |
|---|---|---|
| Can it be fixed? | Yes, it can. | No, it can't. |
| Should the doors be locked? | Yes, they should. | No, they shouldn't. |
| Must the report be typed? | Yes, it must. | No, it doesn't have to be. |
| Will the package be delivered today? | Yes, it will. | No, it won't. |
| Could the problem be solved? | Yes, it could. | No, it couldn't. |
| May the photos be taken here? | Yes, they may. | No, they may not. |
The negative short answer for "Must...?" questions is tricky. We do not say "No, it mustn't" (which means prohibition). Instead, when there is no obligation, we say:
✔ "No, it doesn't have to be." or ✔ "No, it needn't be."
✘ "No, it mustn't." (This means "It is forbidden," which is a different meaning.)
Passive Voice Modals vs. Passive Voice Tenses
Students often confuse the passive voice with modals and the passive voice with regular tenses. While both follow the pattern of "be + past participle", the way "be" behaves is quite different. Let us compare these two structures side by side so you can see the distinction clearly.
| Feature | Passive with Modals | Passive with Tenses |
|---|---|---|
| Formula | modal + be + V3 | am/is/are/was/were + V3 |
| "Be" form | Always be (base form) | Conjugated: am, is, are, was, were |
| Subject-verb agreement | No change — modal never changes | "Be" changes with the subject |
| Negative | modal + not + be + V3 | am/is/are/was/were + not + V3 |
| Question | Modal + subject + be + V3? | Am/Is/Are/Was/Were + subject + V3? |
| Example (present) | The door can be locked. | The door is locked. |
| Example (past) | The door could be locked. | The door was locked. |
| Example (future) | The door will be locked. | The door is going to be locked. |
| Meaning | Adds ability, possibility, obligation, etc. | States facts about past, present, or future |
After a modal verb, "be" always stays as be. It is never conjugated.
Without a modal, "be" must be conjugated to match the subject and tense (am/is/are/was/were).
✔ The letter can be sent today. (modal → "be" stays as "be")
✔ The letter is sent every day. (no modal → "be" is conjugated)
✘ The letter can is sent today.
A common error is combining a modal with a conjugated form of "be":
✘ The cake must is baked for two hours.
✔ The cake must be baked for two hours.
✘ The children should are picked up at three.
✔ The children should be picked up at three.
| Passive Type | Example Sentence |
|---|---|
| Present Simple Passive | The classroom is cleaned every evening. |
| Past Simple Passive | The classroom was cleaned yesterday. |
| Can + Passive | The classroom can be cleaned in ten minutes. |
| Must + Passive | The classroom must be cleaned before the inspection. |
| Should + Passive | The classroom should be cleaned more often. |
| Will + Passive | The classroom will be cleaned tomorrow morning. |
Think you've mastered Passive Voice with Modals? Put your knowledge to the test with our interactive quiz featuring 25 carefully crafted questions.
Take the Quiz