A Guide to Auxiliary Verbs in English

The auxiliary verb is an essential part of communication in English. Auxiliary verbs include words such as do, be, and have. They are often referred to as helping verbs, and they assist us in both everyday communication and more advanced English use.

Modal verbs like can, should, and would are also auxiliary verbs. They layer our sentences with nuance and reveal whether an action is possible or allowed. We also use them to make our language more polite and less direct.

Although auxiliary verbs are absolutely necessary for even basic communication, they are often difficult to master. Read on to learn the ins and outs of auxiliary verb use and improve your English skills!

What are auxiliary verbs?

Auxiliary verbs, also called helping verbs, support the main verb of a sentence. They give us information about the action in a sentence, including:

• when the action takes place and if it’s still ongoing
• the order of actions in a sentence
• how the action is done or should be perceived
• whether the action is in the active voice or passive voice

Auxiliary verbs are also needed to form questions and negative statements.

The main auxiliary verbs are to be, to have, and to do. Modal verbs are also auxiliary verbs – these are words like will, can, and should.

Auxiliary verbs and tenses

We use auxiliary verbs to create complex English verb tenses.

Verbs in the past simple and present simple tenses don’t require an auxiliary verb. They’re expressed using the simple present or simple past form of the verb.

Present simple verb examples:

• They live in the United States.
• _She works in downtown Los Angeles.
• We call each other every week.

Past simple verb examples:

• You did an excellent job on the presentation Monday afternoon!
• He spoke to the neighbors yesterday morning.
• I rode the bus to work all last week.

Review our detailed guide on irregular verbs in English if you need a quick recap!

The auxiliary verb ‘to have’ for perfect tenses

The present perfect tense indicates that an action started and is still ongoing, or that it’s relevant at the moment of speaking. We also use it when discussing past experiences without providing a specific time, or to express the length of time something has occurred.

In order to say anything in the present perfect tense, you have to add the the auxiliary verb have or has before the main verb:

• I have lived in Toronto for 10 years.
• They have learned English thanks to Busuu.
• She has finished the report already.

As one of the narrative tenses, we use the past perfect to describe a past event that happened before another past event. You must use the auxiliary verb had to construct the past perfect tense:

• We had left the house by the time they arrived.
• Jones had already spoken to Martha before I learned of the matter.
• The dog had eaten the food just 5 minutes after you left!

The auxiliary verb ‘to be’ for past and present continuous

Continuous tenses indicate that an action is temporary and in progress (or was in progress) at a specific time. We also rely on the present continuous to talk about future plans.

We use the auxiliary verb to be in the continuous tense structure.

Present continuous examples:

• Everyone is running outside to check out the fireworks.
• I’m taking an Italian class this semester.
• We’re graduating next year.

Past continuous examples:

• Teachers were teaching via Zoom during the pandemic.
• My husband and I were visiting his relatives when he received the news.
• The plants were growing rapidly during the summer.

We can combine both auxiliary verbs (to have and to be) to form perfect continuous tenses.

Present perfect continuous examples:

• The city has been trying to help its citizens during the crisis.
• Environmental activism has been gaining momentum over the past decades.

Past perfect continuous examples:

• Steven had been studying medicine for 3 years when he decided to switch to law.
• Fans had been waiting for a miracle win since the middle of the season.

Take a look at our comprehensive list of verb conjugations in English to review English tenses in-depth.

Modal auxiliary verbs

Modal verbs are another type of auxiliary verb. Depending on the modal auxiliary verb used, we can show whether an action is required, possible or permissible, and if the subject is able or unable to perform an action. Let’s look at how different modal verbs are used in daily communication.

Will

Will is the only one of the modal auxiliary verbs that tells about the time an action occurred. It is used to express the future simple.

• I will do the laundry tomorrow.
• She will visit me next summer.

We can combine will with the auxiliary verbs to have and to be to form complex future tenses:

• They will have graduated by this time next year. (future perfect)
• The celebrity will be signing autographs tomorrow. (future continuous)

By the end of this year, I will have been studying English for 5 years. (future perfect continuous)

Can and could

The modal verb can tells us that something is possible or is allowed in the present, while could is used to discuss ability and possibility in the past:

• Children can learn things more quickly than adults.
• You can swim on the beach until 7pm.
• The employees could workfrom home in 2022.
• My husband couldn’t enter the building last night.

Could may also be used to express politeness when giving a suggestion or asking for help:

• Could you help me with this?
• She could ask for more time off.

Would

Use would to describe a past habit (similar to used to):

• Every day after school, I would go to the supermarket and get some snacks.
• When I was younger, learning a language would entail writing conjugation tables in a notebook.

Would is commonly found in conditional statements:

• Employees would appreciate it if they got more vacations.
• Concerts would be more enjoyable if people didn’t use their phones to record them.

Add would to make a polite request, give a suggestion or state an opinion:

• Would you be my Valentine?
• You would make a great teacher!

Express a desire with *would*:

• They would love to spend the rest of the day exploring the city,
• The customer would appreciate it if you spoke with her.

Should

The auxiliary verb should is used to give a suggestion or recommendation. Use should to make polite requests:

• We should head home. It’s getting late.
• Tom should go back to school to get a degree.

Might and may

Similar to can and could, might and may are also used to suggest that something is possible. They are often used interchangeably. Nevertheless, they each express specific meanings depending on their use.

May is used to:

• Note a strong possibility or infer a future action
  Congress may vote on the matter tomorrow if there is enough momentum.
  This color for the wall may clash with the rest of the furniture.
  

• Give permission
  You may start your exams now.
  The students may take a short vacation as long as they complete their assignments.
  

• Express a wish
  May the force be with you.
  May your hopes and dreams come true.
  

• State a possible result
  If I have some free time tomorrow, I may organize my closet.
  If we don’t bring in more sales, we may have to change our strategy.
  

Might is appropriate when:

• Suggesting something is a possibility, but with less certainty than may
  I might run into her at the party, but I’m not sure.
  There might be a snow day tomorrow for the kids.
  

• Forming second and third conditionals
  If I were a millionaire, I might donate more to charities.
  He might have been a singer if he had taken voice lessons when he was younger.
  

• Report what someone said
  They said they might stay longer if they found a place to stay.

Want to use modal verbs to sound more polite? Learn more about formal and informal language in English.

Other uses of auxiliary verbs

Beyond these many functions, auxiliary verbs are also needed to ask questions, express negative statements, and write sentences in the passive voice.

Auxiliary verbs and questions

When forming questions with tenses or actions that already use auxiliary verbs, we simply switch the subject and the auxiliary verb:

• Lexi is working the late shift.
  → Is Lexi working the late shift?
  

• We can travel by bus to Denver.
  → Can we travel by bus to Denver?
  

• The baby had been sleeping for hours when I arrived.
  → Had the baby been sleeping for hours when I arrived?
  

• The United States will be hosting the Olympics in the next decade.
  → Will the United States be hosting the Olympics in the next decade?

For ‘wh-’ or open-ended questions in English, we simply add the question word in front of the auxiliary verb:

• When is Lexi working the late shift?
• How can we travel by bus to Denver?
• Where had the baby been sleeping for hours when I arrived?
• Why will the United States be hosting the Olympics in the next decade?

We use the auxiliary verb to do to form ‘yes or no’ questions and ‘wh-’ questions when an auxiliary verb is not already used to state the action:

• Do you know what time it is?
• Does the writer express his opinion in the piece?
• What nutrients do fruits and vegetables provide us with?
• Where did Charles Darwin go during his travels?
• How did you learn to speak English so well?
• Did the guests arrive at the party on time?

Negative statements and auxiliary verbs

We also add the auxiliary verb to do in front of the main verb when forming negative statements and questions in English. Its present form is does or does not, and the past form is did not.

• They didn’t call the parents until the situation was under control.
• My favorite TV show doesn’t start until 7pm.
• Why doesn’t this airline fly out of LAX?
• Didn’t you get the message I sent you last weekend?

As with positive statements or questions, statements that already include the auxiliary verb do not need an additional auxiliary to be negated. We simply add the word not after the modal verb. The only exception is will, which changes to will not or won’t in the negative.

• The Mona Lisa isn’t as large a painting as everyone expects.
• You won’t believe what I’ve got to tell you!
• Young children shouldn’t spend too much time looking at screens.
• Haven’t the police been made aware of the situation yet?
• Were you not busy when they called last night?

Using the verb to be in the passive voice

When we want to express an action in the passive voice, we use the auxiliary verb to be followed by the past participle. To be is conjugated depending on the tense of the sentence.

• present simple passive – This building is owned by a group of siblings.
• present continuous passive – Sandra is being tutored by a student in a higher grade.
• present perfect passive – One of my car’s tires has been stolen!
• past simple passive – My hair was cut by a great hairstylist.
• past continuous passive – Pamphlets were being handed out in front of the library.
• past perfect passive – The news hadn’t been broadcast to the general public.
• future simple passive – You will be informed of the decision via email.
• future perfect passive – The packages will have been delivered before the holidays.

Avoid overusing the passive voice and stick to the active voice whenever possible. See our article on when and when not to use the passive voice in English.

Tips on using auxiliary verbs

The first step to mastering auxiliary verbs is to follow the rules above and use each one in the appropriate situation.

Here are some additional tips to keep in mind.

1. Don’t leave out the auxiliary verb

People often mistakenly leave out auxiliary verbs in spoken English.

• She being rude to me! → She is being rude to me!
• We not go to the mall every weekend. → We do not go to the mall every weekend.
• Where the doctor go? → Where did the doctor go?

2. Conjugate do, be, and have for the third-person singular

The form of do, be, and have is the same for all subjects except the third person singular (he, she, it).

❌My dog don’t like staying outside long.
✔ ️My dog doesn’t like staying outside long.

❌The councilman’s secretary have been communicating with the other council people.
✔ ️ The councilman's secretary has been communicating with the other council people.

❌Are the plumber working on the downstairs bathroom?
✔ ️ Is the plumber working on the downstairs bathroom?

3. Don’t conjugate the main verb In questions, negative statements, and sentences with modal auxiliary verbs, the main verb is in the bare infinitive form (the verb without to, like travel, go, study, and so on).

• They couldn’t join the others on time so they got seats in the back of the theater.
  → Not ‘They couldn’t joined’
  

• Doesn’t your sister work at the French embassy in Washington?
  → Not ‘Doesn’t your sister works’
  

• He won’t find his birthday present if we hide it in the basement.
  → Not ‘He won’t finds’

An exception is perfect and continuous tenses, where the main verb is the past participle or a gerund form, respectively.

4. Do not add to after an auxiliary verb

We don’t add the word to between the auxiliary verb and the main verb:

• We should to go to the cinema. [Incorrect]
  We should go to the cinema. [Correct]
  

• The professor will to assign new homework next week. [Incorrect]
  The professor will assign new homework next week. [Correct]
  

• These shoes don’t to match the dress. [Incorrect]
  These shoes don’t match the dress. [Correct]
  

Learn your auxiliary verb rules

Learning to use auxiliary verbs correctly takes practice. However, they’re an essential part of English grammar, so try to get the hang of them before moving to more advanced English grammatical topics.

The auxiliary verbs to be and to have allow us to form complex tenses like the perfect tense and the continuous tenses. The verb to be is also key to constructing the passive voice.

We rely on the helping verb to do to create questions and negative statements in the past and present when no other auxiliary verbs are part of the verb.

We add modal auxiliary verbs like can, should, and would to our sentences when we want to indicate something is possible, probable or permissible, and to express many other ideas.

Study each use of auxiliary verbs carefully, and look at plenty of examples. Since they are so common in everyday communication, you’re sure to get the hang of them with practice. Happy learning!