Subject-Auxiliary Inversion: 5 Examples That Will Make It Clear

Subject-Auxiliary Inversion

Today, we’re looking at subject-auxiliary inversion (SAI), also called subject-operator inversion. Maybe you’re thinking, “What’s a subject-auxiliary inversion?”. Don’t worry, you’ve seen it before because we use SAI every time we make a question in English.

Subject-auxiliary inversion is a sentence structure where the usual order of the subject and auxiliary verb is reversed. This means that instead of the subject coming before the auxiliary verb, the auxiliary verb comes before the subject.

For example:

  • Peter does enjoy the movie.
  • Does Peter enjoy the movie?

How to use subject-auxiliary inversion in English?

1. In questions, question tags, and echo questions

We use subject-auxiliary inversion when we make a question:

  • Do they have any pets at their house?
  • Did they finish their project on time?
  • Have you met my brother before?
  • Are you going to the gym later?
  • Can I borrow your pen for a moment?
  • Shouldn’t we leave now to avoid the traffic?

All of these sentences use auxiliary verbs such as do, did, have, are, and modal verbs such as can and should (because modal verbs are a form of auxiliary verbs) that are inverted in questions.

Question tags are another situation in which we invert the auxiliary verb and subject:

  • He didn’t like the movie, did he?
  • You don’t know him, do you?
  • You’re coming to the party, aren’t you?

We also use inversion in echo questions:

  • I would like a cup of tea. Would you?
  • Olivia has got a MacBook. Has she

I just wanted to mention that we use inversion in those situations, but most people are familiar with all of them.

2. Subject-auxiliary inversion with negative elements

Many people are not familiar with the fact that to express surprise, shock, or to emphasize that something has never happened, we say something like this:

  • At no time did you ask me for permission.
  • Not once did he say thanks.
  • Not only was he rich, but he was also a very pleasant person.
  • Under no circumstances should he exercise.

We start with negative elements such as not once, at no time, not only, and under no circumstances and then we invert the subject and auxiliary verb. It sounds quite formal and literary in many contexts, and it works well in a letter of complaint or similar texts.

3. SAI after restrictive adverbs

The use of subject-auxiliary inversion after restrictive adverbs such as scarcely, hardly, seldom, really, never, no sooner, barely, only, and little is similar to the use of inversion with negatives because it emphasizes and strengthens the point that something has never been seen before or that there was little knowledge of something.


  • Little did I know, he was actually French.
  • No sooner had we arrived than dinner was served.
  • Never have I seen such a wonderful view.
  • Rarely has he seen her.
  • Only afterward did I learn the truth. 

4. In hypotheticals (2nd/3rd conditional)

Subject-auxiliary inversion is commonly used in hypotheticals to express a situation in the present, future, or past that is unlikely or impossible.


  • If I had more free time, I would learn a new language. (2nd conditional) → Had I more free time, I would learn a new language. (SAI)
  • If we had left earlier, we wouldn’t have missed the train. (3rd conditional) → Had we left earlier, we wouldn’t have missed the train. (SAI)

Just remember to remove the “if” from the original sentence when using subject-auxiliary inversion.

5. When expressing agreement and disagreement

Subject-auxiliary inversion when expressing agreement or disagreement is a common structure in English and is essential for clear communication. In this case, we often use the words “so” and “neither” to indicate agreement or disagreement with a previous statement.

  • A: I love fish and chips. Do you? 
  • B: So do I.
  • A: I would like a cup of coffee.
  • B: So would I.
  • A: I can’t swim. 
  • B: Neither can I

Therefore, we also make these inversions when we agree or disagree with someone.

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